US2435747A - Method and apparatus for sealing containers - Google Patents

Description

Feb. 10, 1948. c. H. LARSON I METHOD AND APPARATUS FOR SEALING CONTAINERS Filed June 25 1943 2 Sheets-Sheet 1 PURIF/Ef? Carl Elaream Feb. 10, 1948. v c; H. LARSON 2,435,747.

METHOD AND APPARATUS FOR SEALING CONTAINERS Filed June 25, 1943 2 Sheets-Sheet 2 1., a N V w 7 W m y w 6 5% v m a 1 0 a M w i w I N H l v g 1 f: K W \i 5 E 9 46 5 J a M w 4 1 3 mm Q g N \N igssa gs Patented Feb. 10, 1948 METHOD AND APPARATUS FOR SEALING CONTAINERS Carl H. Larson, Elkhart, Ind., assignor to The Adlake Company, a corporation of Illinois Application June 25, 1943, Serial No. 492,330

10 Claims.

This invention relates, particularly, to a meth-' d and apparatus for making hermetically sealed an inert gas, such as hydrogen, helium, argon, or

the like, and then hermetically sealed. In glassenvelope, mercury switches, the sealing off is ordinarily done by fusing the upper side walls of the envelope closed after the proper gas fill has been introduced into the envelope through the open end. But in metal switches, this convenient method of forming a hermetic seal cannot readily be used.

The primary object of this invention, therefore, is to provide a method and apparatus which will facilitate the evacuation and/or pressure filling of a switch envelope or other container and the subsequent hermetic sealing of the container when the proper state of evacuation or gas fill has been obtained within the container. More specifically, it is an object of the invention to provide means for evacuating and/or pressure filling metal containers and subsequently hermetically sealing them.

Further and other advantages and objects of the invention become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawings in which Fig. 1 is a diagrammatic view showing a pre-' ferred form of the invention;

Fig. 2 is a fragmentary view showing the manner in which adapters may be used to accommodate containers and envelopes of difierent sizes;

Fig. 3 is a sectional view showing a metal-envelope mercury switch which is suitable for use with this apparatus;

Fig. 4 illustrates the manner in which a die can be substituted for the welding contact on the movable head of the machine for crimping over the upturned end of the container to form a hermetic seal;

Fig. 5 illustrates a container hermetically sealed in this manner;

Fig. 6 shows a mercury switch which is sealed by crimping rather than by welding.

But the specific illustrations shown in the drawings and hereinafter described will suggest to those skilled in the art other forms of the invention within the scope of the appended claims.

In the preferred form of the invention, which is diagrammatically shown in Fig. 1, the machine consists of a frame generally designated III which may be of any convenient construction, but which is here shown, for the purpose of this disclosure, as consisting of a base member II and an upper member l2 which may be conveniently disassembled for access to the interior of the machine and which are normally held together by bolts I3. Access openings are provided wherever necessary or desirable.

Within the frame is a two-part chamber or enclosure generally designated 14 consisting of an upper part l5 which is fixed to a flange l6 of the member l2, and a lower part I! which is supported through a rod IS on a piston [3 which travels within an air cylinder 20. Downward movement of the piston I9 opens the chamber 14 at the point 2| just above the rubber gasket 22 which is recessed into the enlarged top face 23 of the part II.

The upper part l5 of the chamber or enclosure has a diaphragm wall 24 through which a movable head 25 is hermetically sealed and movement of the head 25 is controlled by a piston 26 which travels within a cylinder 21 mounted on the top wall of the frame l0 and is connected to the head 25 through a rod 28.

The lower part 11 of the chamber I4 is re cessed, as shown at 29, to provide a pocket or support for the container 30 which is to be hermetically sealed after receiving the appropriate gas fill.

Before describing the method in which the machine is used to evacuate and/or gas fill a container which is then to be hermetically sealed, it will .be helpful to understand the precise construction of an illustrative form of mercury switch which may be advantageously handled by the machine.

Referring, therefore, to Fig. 3, it will be seen that the switch comprises a tubular envelope 32 of non-magnetic material, preferably 18-8 stainless steel, and having both ends of the envelope beveled off as indicated at 33. A base 34 is formed, by stamping, into a cup-shaped cap as shown and it has a central opening 35 through which an electrode 36 is sealed by a heat sensitive material. Preferably the electrode 36 is made of molybdenum. It is desirable to use a heat sensitive sealing material and a metal for the base 34 which have a coeflicient of expansion substantially the same as that of the molybdenum electrode. However, other combinations of material may be used for the sealing of an electrode through a.

base but in any case, the sealing material is likely to be heat sensitive and must be protected when the base 34 is heat joined, as for example by torch welding, to the reduced end 33 of the switch envelope. The means for heat joining the base to the envelope without damaging the electrode seal is of nqparticular consequence here and does not require specific description.

A glass sleeve 38 is telescoped over and fused to the electrode 36, and since the electrode material and glass are chosen with like coefiicients of expansion, the glass will adhere to-the electrode, without cracking even under severe temperature changes. The glass sleeve38 is enlarged near the lower end 39 of the electrode. to iorma: bead 3! which, with the proper application of heat may be firmly fused to the seat 4'9 of the base 3 4', with a portion of the glass overlaying and interlocked with the top margin 4| thereof, thusforming a strong and secure insulated bond for the --electrode and the base 34 'Lead' wires 32 and d3: are soldered to theelectrode 36 and base '34, respectively, so: that the switch envelope itself forms one sideofran elec- -trical-circuitand the exposed end 44 ofithe electrode 36 forms the-other side of thecircuit. .A ceramic cup 48 is fused to the top of the sleevetfi and-contains a body of mercury llfl which isin constant contact with the exposed endrfi l of the electrode- 36. =A magneticallycontrolled displacer 46 is moved vertically within the envelopeto shift 'the level of the main body .of mercury 145, and i when the mercury level rises sufficiently to. cause mercu-ry toflow over-the top of the cup 48, the

electrical circuit is closed, and when that-condition does not exist, the circuitvis open.

A time delay thimble, generally :d'esignatedzilt is tel-escoped over-the upper portion of the electrode 3-6 to delay theomovement. otmercury to and/or'away from the mercury: 4:15. in the cup 458 in proportion to the time required forges to. pass through the ceramic plug-. 50 mounted in the. top of the thimbl'e-AB to equalize the gas pressure dif- -f-e-rential caused by shifting of themercury; level by: the displacer. Since the present. invention is notconcerned with theparticular details of, the time-delay means, itv will be suflicient to; refer to Larson Patent No. 232,814 tor a fuller-disclosure "of this structure.

:The plunger ord'i'splacerrlr is:.preferably made. "of high grade magnetic ironand it isprovided at bother-ids with a reduced portion 5! adapted; to receive a non-magnetic steel spring 52 which, is

- frictional ly held on the reduced portion-5t of, the -displacer. 'The -springs.\52;..may bemade of the same material as. the switch envelope 3.2 namely, t8 8 stainlesssteel.inthe austenitic formwand the use of this material:.prevents the..displ'acer 4:5

from adhering to the top closure 53 when it is made of cold rolled steel or other magnetic material.

In making up. a metal. switchof the type shown overthe lower end of the insulated el'ectrodeand ahead isformed adjacent. to. the lower; end 39. Theelectrode assembly is then invertedarrd the base is drawn upwardly toward the end 39. of

the electrode tobefused with and bonded; to; the

bead formedat that. end of the. electrode. The

complete sub-assembly consisting ofthe ibase' ii and the: electrode" bondedtherethroughzwith the time: delay. structure; mounted on the. upper end from the envelope during the evacuation and gas "ifillingioperation.

aloose fitting steel Weldingpin orbrad 56, as

shown in Fig. 3; Whenthis pinis in place, it is sufficiently loose fitting so that gas may be withdrawn from the otherwise hermetically sealed en- ..velopeor. introduced into the envelope without substantial delay but obviously, if desired, the

head of the pin could be given a. special shape to insure proper ingress and egress of the gas Referring now to Fig. 1, it will be seen that by opening the chamber M through the lowering of the piston [9, the switch 30 may be inserted in the. pocket. 29' into: the base of which a spring 5'! xmay beplacedto resiliently support the switch against the. pressure exerted by the head 25 when it islowered to act. on the switch. If anextremely short switch is being worked upon; a plug58 (Big. 2) mayhe'dropped into the bottom of the pocket -2'9.-.and .the plug shouldhave a screw threaded opening--59 to facilitate its'remo-val. Also, if the switch :has :a smaller diameter than the bore of the pocket.'29,.a spacer sleevefifl'maybe inserted into 1 the pocket to accurately: accommodate the switchtfi.

After. the switch 3fi-is in placeiwithi-n the pocket 29,. air, .or-some other fluid under pressure,v is introduced into the lower .partyofthe cylinder 20 from a source towhich pipe. fil leads through adual valve 62 and pipe 63,-the valve 62, at'the same time, placing the pipe 64. leadingfrom. the upper part of the cylinder 20ein'communication withthe atmosphere in the; conventional way. Thepistonthereupon urges the lower part, i!

.ofthe chamber against the upper part with a .force proportional to the'pressureqof air within the line ,fil'andthe rubber gasket 22 makes the chamber gas tight.

With the switch in place; thechamber is then evacuated by pump 6-5:which-is connected to the chamber through; a: pipe 66 and two-way valve When the proper vacuumhas been drawn, as determined by a Tesla. coi1768,;which produces a dischargein a small glass side chamber 69 which is iii-communication with the interior of the chamber I4 througha bore-l0, the valve 6'! is turned torplace, the chamber I 4 in communication withthe gas which is, togbeused for filling the envelope 30. This: gas-which; may behydrogen,

--heiium,argon, or the likes may be stored in a taneously withdrawn with the air or gas, within the. chamber i' landrlikewi'se, when the chamber l'4- ispsu'biected tothe gas; fromthey tank H, the

envelope immediately fills withsuch gas and :acquires: the same pressure. as the gas within the chamber l4. During; the evacuation stage,

-the. envelope 3llsmay be heated. by a resistance coil 16 or an induction coil; maybe used, if desired.

.Qrdinarily it will sufiice to heat the envelope -1=with "its contents outside of thermachine and .place it; intos the: machine. while: not but; resistance. coil or. induction CDi'I hBatiIIEiH' situ may: be used; if

desired. If a high frequency induction coil is used, it may be located either inside or outside of the part ll of the chamber I4.

After the switch envelope has been flushed out with the pressure being shown on a gauge 11.

The switch envelope is then ready for being hermetically sealed.

The head 25 carries a welding contact I8 and is hermetically sealed through the diaphragm wall 24, which is preferably made of heavy rubber and is clamped by bolts I9 between the flange or web I6 of the frame and a mating flange 80 on the upper part I5 ofthe chamber I4. The

head is movable up and down by proper manipulation of a dual valve 8|, similar in all respects to the valve 62 and connected on one side to the compressed air supply through a pipe BI and on the other sidethrough pipes 82 and 83 with the upper and lower sides, respectively, of the piston head 26. As is the case with the valve 62, when one side of the piston is open to the compressed air supply through a pipe 6|, the other side is placed in communicationwith atmosphere through the valve and, of course,'the valves 62 and 8| have off positions in which both sides of the pistons are shut off from theair supply.

With the propergas fill supplied to the switch envelope 30, the valve 8| is turned to force the welding contact I8 into direct contact with the pin 56 in the top closure 53 of the envelope and an electrical circuit is then closed by pushing a button 84 to provide a correctly timed welding impulse to the contact I8. This causes the pin 50 to be welded to the cap 53 and thereby hermetically seal the envelope. The timing cycle is controlled by a timer 85 and upon closing the primary of the transformer 86 by pushing button 84, the impulse is induced in the secondary 81 of the transformer to produce the weld, As may be seen in Fig. 1, one side 88 of thesecondary is connected to the head 25 through the rod 28 which is insulated from the frame by insulating members 89 and 90 and the other side 9| of the secondary is connected to the chamber base H which is also preferably insulated from the frame by insulators 92, 93, 94 and 95.

In the described welding procedure the head 25 carrying the electrode or contact I8 moves towards and against the container 30 a predetermined distance. The spring 51 acting against the container exerts predetermined force in opposition to the predetermined movement of the welding contact I8 and thereby serves as means to cause predetermined weldingpressure to be created in response to the predetermined movement of the welding contact. Such an arrangement insures welding pressure of a desired magnitude and insures uniformity of pressure through successive welding operations.

It is also possible to use the machine and method of this invention to hermetically seal switch envelopes or other containers by a crimping process as distinguished from a welding process. This is shown in Figs. 4. 5 and 6, the latter figure showin a mercury switch structure suitable for this type of operation and the other two figures showing any type of a container which it is desired to hermetically seal. 7

Referring first to Fig. 4, a container I00, which is made of metal or other deformable material, is

provided with an enlargement IOI adapted to receive a rubber gasket I02 sandwiched between tionship to the container.

upper and lower metal discs I03 and I04. respectively. The top margin of the enlargement IOI extends above the disc I03 and the head 25 of the machine is, in this case, equipped with a die I05 having a rounded die face I06 which, when brought down upon the container I 00, as it is supported in the form I01, crimps over the top margin .of the enlargement IOI and forces the rubber gasket outwardly against the side walls of the enlargement to form a tight seal. The crimped over portion I08 sets firmly upon the top disc I03 and permanently holds the gasket I02 in sealing rela- The bottom disc I04 protects the rubber gasket from the contents of the container I00 and vice versa and also forms a seat for the gasket during its compression.

The mercury switch shown in Fig. 6 is formed in much the same manner as described for the container in Figs. 4 and 5 but in this case. the container or envelope I09 is preferably stainless steel in it austenitic form. It is also provided with an enlargement I I0 at its open end thus providing a seat III upon which the electrode assembly generally designated II2 rests. This assembly consists of an electrode II3, preferably of or otherwise secured and the disc fit within a recess I I5 formed in the bottom face of a ceramic or plastic insulator IIB over the top surface of which is placed an annular metal disc Ill.

The lower face of the insulator IIG rests upon a rubber gasket II8 which, in turn, rests upon a metal plate I I9 seated upon the ledge III of the envelope I09 and having a dished-out portion I20 adapted to receive and support a ceramic plug I2I which tightly fits over the electrode H3 and prevents contamination of the mercury I22 within the envelope by the rubber gasket H8.

The envelope I09 is first filled with the correct amount of mercury I22 after which the plunger or displacer I23, which is made of magnetic material, is placed in the envelope. The electrode assemblv H2 is then slipped into place and the upstanding margin of the enlargement I I 0 is then crimped over, as shown at I24, by use of a suitable die (not shown) having a die face similar to the die face I06 shown in Fig. 4. The crimping over of the upstanding margin is accompanied by the application of pressure which forces the rubber gasket outwardly to effectively seal the in erior of the envelope from the atmosphere. If de ired, hard solder may be applied to the crimped-over portion of the enlargement I I 0 as shown at I 26.

Obviously the machine and method of the invention has many applications, and can be variously embodied within the scope of the appended claims.

Iclaim:

1. In apparatus for making hermetically sealed containers, the combination of a two-part enclosure separable for access therein and having a pocket adapted to receive the container to be sealed. a yieldable wall forming part of the enclosure, said wall having an aperture therein, a

movable head extending through said aperture frame, a. two-partchambenpne part being fixed phragm to theother in fluid-tight engagement therewithiorvmovement towards the container inthe chamber to seal. the container while the container -content'correspends to the chamber content,

.3.. In apparatus-of the class described,.a frame,

:a twee-part chamber, one part being fixed to the framenand theother. part being movable to and from the fixed part, means for sealing the chamber When the two parts thereof are together,.passage means extending into the chamber for fluid 'fiowinto andv out of the chamber whereby the chamber may be -evacuated and/or filled. with a gas, a. diaphragmserving as a wall of saidcham- .ber, amovable headsealed to said diaphragm and extending through the diaphragm from one side .of. the diaphragm to the other for movement to- :wardsandaway fromacontainer in the chamber to sealzthe container while the containercontent corresponds'to the gaseous content of the chamber.

4. lneapparatusof the class described, a frame,'

a first fluidpressureFactuated means -mounted fromthe upper portion of the frame, a second ,fluid-pressure-actuated means mounted from the lower portion of the,- frame, a two-part chamber, one part being fixed to the frame and the other part-being; movable to and from the fixedpart by said lower fluid pressure-actuated means,

passage means for fluid flow into and out Of said chamber whereby the chamber may be evacuated .and/orfilled; witha gas, a diaphragm serving as a wall of. said chamber, a movable head sealed to said 1diaphragm..and extending through the diaphragm from one side of the diaphragm to the. other, saidmovable head being operatively connected with saidfirst fluid pressure-actuat- 'part substantiallyfluid-tight inclosure separable for access thereinto and having a pocket adapted to' receive a container to be sealed, said chamber and pocket being dimensioned in depth to permit the container'to move'towards and away from the pocket bottom while the two-part enclosure is closed, electrode means in said chamber adapted to. be actuated from the exterior thereof for movement towards and away from the pocket bottom for sealing action on said container,

yielding means in. said pocket for contact with said container to urge the container awa from the pocket bottom thereby to resist said movement of theel'ectrode means with predetermined pressure, and. means for, causing current to flow between. said electrode. means and said container "While. the container. is subject to. said predetermined pressure.

. 6. In. apparatus .of the class described,v a cham- .ber composedof, amultiple-part enclosure separable to opento receive an unsealed container and to Hclose for enclosing the container, a diaphragm serving as a wall of said chamber, pas- ,sagemeansfonfiuid flow'intoand outof said *8 chamberwhereby. the chamber may be evacuated and/or filled with a gas, :means extending through said diaphragm. in a fluid-tight manner foractuation from the exterior of. the chamber to move towards and. awayfrom. said container for sealing action onthe container involving pressure, means to actuate. said, sealingmeans for predetermined movement toward saidcontainer, andyiel-ding means in said chamber acting against said container to yieldingly-resist said predetermined movement with predetermined force. thereby causing predetermined. sealing pressure against the container: in-response-to said predetermined movement.

7. A method of fabricating a hollow metal device of the character described -.i-ncluding the steps of, completing the device with a'smal'l. port through. a metal wall thereof, placing-a headed plug in said port with the head of the. plug-outside the port and with the stem extending into the'port in a non-sealing manner, enveloping said device with said plug inplace .in agaseous environmentof a character gcorresponding to..a gaseous content desired inthe device,.:exerting pressure on said head, and simultaneously-heating said head to weld the-head to the;device thereby to seal the device while in said-environment.

8. A method of fabricating a hollow -metal device of the character. described including the steps of, completing the device with a small port through a metal wall thereof, placing a'headed plug at said port with-the stem of theplug extending into the portwi-th fluid-passing clearance and the head of the plug outside the port, moving said device with. said plug in place into a gaseous environment of a character corresponding to. a gaseous content desired in the device, exerting pressure on said head, and simultaneously heating said head to Weld the head to the device thereby to seal the device while in said environment.

9. A method of making hermetically sealed metal containers having a gaseous content which consists in placing a container in an enclosure with the container completely sealed except fora small opening, placing a headed welding pin in said opening with sumcientclearance around the pin to. provide open communication between the interior of the container and the enclosure through said opening, establishing in said enclosure a gaseous state corresponding to a gaseous content desired within the container, and then when such state is established welding said pin to the container to hermetically seal the container.

10. In apparatus for making hermetically sealed sheet metal containers,thecombination of an enclosure made in parts that are separable. for access to the interior thereof and .adaptedto hold therein. the container to be sealed,. passage means for fiuid flow into and outofthe enclosure whereby the enclosure may be. evacuated and/or filled with a gas, a flexible diaphragm serving. as a wall portion of said enclosure, a sheet metal forming die within the enclosure, andmeans extending through the diaphragm from oneside thereof to the other in a fluid-tight manner for operating said die whereby-the diemaybe actuated through the diaphragm'for sealingthecontainer while the: enclosure is closed.

.CARL LARSON.

I (References on following. page) 9 REFERENCES CITED Number The following references are of record in the file of th1s patent: 2,262,176 UNITED STATES PATENTS 5 2,047,260 Number Name Date 2,014,597 Staley Sept. 17, 1935 2,101,156 Payne Dec. 7, 1937 Number 2,326,296 Harrison et a1 Aug. 10, 1943 507,307

Name Date Badger Feb. 3. 1931 Staley Jan. 24, 1933 Geiger et a1 Nov. 11, 1941 Franklin July 14, 1936 FOREIGN PATENTS Country Date France June 18, 1920

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