US2024065A - Metal walled vacuum chamber or container and method of manufacture thereof - Google Patents

Description

2 Sheets-Shet 1 E. L. SCHELLENS METAL WALLED VACUUM CHAMBER OR CONTAINER AND METHOD OF MANUFACTURE THEREOF Filed July 30, 1932 'Illl Dec. 10, 1935.

Dec. l0, 1935. E. L. scHELLENs y 2,024,065

METAL WALLED VACUUM CHAMBER OR CONTAINER AND METHOD OF MANUFACTURE THEREOF Filed July 150,l 1952 2 Sheets-Sheet 2 XR I INVENTOR:

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Patented Dec. 1o, 1935 UNITED STATES METAL WALLED VACUUM CHAMBER R CONTAINER A`ND METHOD 0F MANU- FACTURE THEREOF Eugene L. Schellens, Ridgewood, N. J., assignor to The Shellwood-Johnson Company, Paterson, N. J., a corporation of New Jersey Application July 30, 1932, Serial No. 626,384

14 Claims.

This invention relates to metal-walled vacuum chambers or containers, and method of manufacture thereof, wherein the essential elements are constructed largely, if not entirely, of metal so that the article is strong'and for all practical purposes unbreakable. 'I'he general object of the invention is to provide a metal-walled container or other chamber which can be evacuated to serve for insulating or other purposes and in which the Walls are permanently gas-impermeable to prevent gradual loss of vacuum.

A special object of the present invention isa 'vacuum insulated container having a largeopening so that solid food in large sizes can be introduced and removed therefrom and the interior of the container readily cleaned and so constructed that the separate parts thereof can be brazed or alloyed together in a. manner which insures a permanent vacuum tight seal at the joints between the separate parts.

While metal vacuum insulated containers or bottles have been proposed heretofore such a metal container is not permanently gas tight and the evacuated space of the containervin time loses through the pores in the metal side walls that' out of contact with leach other and forms a clo` container is kept down,

a considerable amount of its vacuum by leakage define the evacuated space so that the insulating value of the space becomes lessened. It is an object of the present invention to provide a metal walled vacuum insulated container with a metal sealing film that is welded t'o or alloyed with Athe metal wall and fills all pores, seams and fissures therein and thus makes the metal wall permanently tight against impairment of 'the evacuated space so that the insulating eiciency of the container is maintained indefinitely.

The container embodying the vpresent invention comprises an inner container or' receptacle enclssed within an outer vcontainer or shell, the space therebetween being evacuated and the top of the inner container being'connected to and spaced from the top of the outer shell by a thini annular metal ring of channel cross-section that is welded to the shell and the container and supports the shell and container in spaced relation sure for the evacuated space therebetween, the

ring being' thin and of relatively high resistance to heat conduction between the lcontainer and the shell so that the flow of heat'into or out of the Such a construction comprises a further object of .the invention.

It is highly desirable to provide the interior surface of the vacuum insulated container with a heat reflecting surface whereby to retard the loss of heat from the contents thereof. With the usual restricted-opening metal vacuum bottle it has not been practicable to electroplate 'and polish the inner surface of the container. In accordance with the present invention, however, the 5 container is so constructed that the inner surface thereof can be electroplated and polished readily whereby to enhance the heat insulating property thereof; and such a construction constitutes an' object of the present invention. 1

Another object of the invention is to provide a vacuum-insulated container with outer and inner metal side walls which enclose the evacuated heat-insulating space, the outer side wall providing'an outer seal or envelope for the evacuated 15 space and being thin so that it offers great resistance to heat flow along its length, the wall being so thin that it cannot be depended upon to withstand safely severe mechanicalimpact and the pressure difference on opposite sides of it, and there being a relatively thick heat-insulating pressure-resisting shell surrounding and intimately connected with and providing support for and protecting the thin metal shell. The thick insulating shell thus, in effect, constitutesthe 25.

' liquids, and another insulated compartment, say, 35

for the reception of solids.

Another object of the invention is the provision of a vacuum-insulated extension that is open at both ends and can be secured at one end to the top of the container and have the-cover -forfthe container secured to the other end thereof, there- 40 by to provide a container of enhanced capacity.

A further object of the invention is the provi-v sion of a vacuum-insulated container having its inner or food containing compartment provided '45 with a heavy wall of high thermal capacity so that it is enabled to store up a large amount of heat or cold, as the case may be, and thereby prolong the time during which the contents of the container are maintained at the desired high or low temperature.

A further object is generally to improve the construction and extend the use of vacuum-insulated containers.

Fig. 1 is-a sectional elevation of a vacuum- 55 insulated container, or vacuum bottle, embody-- ing the present invention.

Fig. 2 is a sectional detail illustrating a modified form of screw-threaded connection between the container and the top cover therefor.

Fig. 3 is a view similar to Fig. 2 but illustrating a modified form of connection between the inner receptacle and the outer shell.

Fig. 4 is an enlarged detail illustrating the vacuum seal and the reecting surface of the container.

Fig. 5 is a sectional detail of a vacuum-insulated extension for the container of Fig. 1.

Fig. 6 is a. sectional view corresponding to Fig. 1, but showing thereof only. the assembled metal wall parts directly enclosing the chamber space.

Fig. 7, on a larger scale, for diagrammatic purposes, shows only portions of two adjoining walls of Fig. 6, before treatment.

y Fig. 8 is a diagram similar to Fig. 'l andindieating the application or distribution of a supply of sealing metal or copper upon` the metal or iron walls.

Fig. 9 diagrammatically illustrates the treatment of assembled chambers like Fig. 6, with copper applied as in Fig. 8, in a heating furnace in reducing atmosphere at a sealing temperature above the melting point of the copper.

Fig. 10 on a microphotographic scale indicates diagrammatically and approximately the porous character of an iron wall and the spreading and sealing action of the copper upon and into the iron surface.

Fig. 11 is a diagram similar to Figs. 'I and 8 showing the result of these steps. with copper sealing the iron walls and bonding the joint between walls, a later step. after plating over the copper, being shown in Fig. 4.

'I'he vacuum-insulated chamber, container/or vacuum bottle embodying the present invention is designed to have its parts welded or bonded together and the pores, passages and the like in its metal walls vsealed by'heating the assembled parts in a reducing atmosphere, such as hydrogen, in

contact with a lower melting point metal, such as copper for parts composed of iron ors'teel, or.

' so that the parts are bonded together when they are cool and the bonding metal is solid, and the passages and the like are sealed against air leakage therethrough.

In accordance with the present invention the vacuum-insulated container 9 illustrated in Figs. 1 and 6 comprises an inner metal container or vessel I0 and an outer metal container or vessel I2, the side walls of which are spacedvfrom the` side walls of the inner container and the chamber or space therebetween is highly evacuated. The inner container il has a side wall that comprises essentially a -cylindrical tube Il that is open for practically its full diameter at the top so that completely free access can be had with the interior thereof. 'Ihe bottom wall of the inner container comprisesa disc Ii which. in the initial assembly of the parts, is frictionally re' tained in the open bottom of the tube Il. The tube Il and the disc I6 are preferably, although not necessarily, composed of steel and are rela- .enter and seal the joints. passages and the like. 5

tively thick and thus have high thermal storage capacity so as to impart heat to the contents of y the inner container or to maintain the contents cool, as the case maybe, for a substantial period of time. 'I'he bottom wall I6 is secured or alloyed 5 with the tube il in the manner described, by heating the parts in a reducing atmosphere with copper present at or near the joint between the parts to a temperature above the melting point of copper whereby the copper runs into the joint l0 by capillary action and forms a strong bond and a vacuum tight seal between the parts. In accordance with the present invention after the disciS has been pressed into the bottom end of the tube i4 preferably the entire inner surface of l5 the inner container I0 has a coating of copper particles applied thereto preferably bymixing the copper particles with a solution of pyroxylin, orisome other satisfactory vehicle that will cause the copper to adhere Where deposited on 20V of the mixture can be sprayed onto the surfaces adjacent the joint between the wall I6 and the tube il. The receptacle i0 is then heated in the 30 reducing atmosphere to above the melting point of the copper and the copper flows by capillary' action notonly into the joint between the tube and the bottom disc I6 but also into all pores, pipes and fissures of the metal surfaces and 35 alloys therewith so that it not only bonds the disc and the tube together but forms a vacuum tight seal for all the pores in the metal walls and thereby prevents leakage of gas therethrough into the evacuated space. This vacuum sealing film 40 is illustrated by the numeral 'I8 in Fig. 4. I have found that this method of sealing the wall against gas di'usion though it is highly effective by reason of the fact that the metal sealing film wets the surface of and alloys with and in eifect sinks 45 into the surface of the .metal wall on which it is applied and thereby eifectually closes all passages through the wall, and that a plated film or one applied in any other manner known to meis not completely gas tight. For some purposes, 50 the bonding and sealing metal, as copper, can be electroplated on the'surfaces of the walls and then fused in the reducing atmosphere, whereby it will be caused to bond to the metal and 'Ihe bonding metal also can be applied before the parts have been assembled so that the metal will be in the joints between the parts when they are assembled and will be fused and spread over the juxtaposed surfaces andailoy therewith in the furnace. After the copper sealing iilm is applied the interior of the inner receptacle is electroplated preferably by chromium, the chromium nlm 2l, see Fig. 4, being deposited upon 85 the copper nlm fil, the copper film not only cony stituting a vacuum seal for the metal wall but' also constituting a necessary base to receive the chromium'film, the electrode for the plating proci.

ess being introduced through the wide open7'0 mouth of the container. After the deposition of the chromium nlm, thelmisbuifed or pol' ished by a tool introduced through the open mouth of the container to receive a high polish whichreiiectstheheatandretardsthetransmis-" outer shell is sufllciently strong and rigid to resion thereof into the wall of the inner container. The electro-deposition and polishing of the chromium film can be accomplished commercially by reason of the wide opening of the inner container. The outer shell I2 comprises a thin metal tube V22 preferably of steel and of uniform diameter from end to end and opens at the top and bottom and spaced from the inner container to provide an evacuated space 24 therebetween. The shell 22 is provided with a cup-shaped metal bottom closure having a substantially flat bottom wall 26 and an upturned continuous annular flange 28 which is fitted or pressed within the open bottom end of the shell.A The flange and shell are welded v or bonded together by copper or the equivalent in the manner described in connection with the inner container and the inner surface of the outer shell, and the closure 26 preferably is provided with a copper vacuum-sealing film and a heat reflecting film in the manner described in connection with the inner container. 'I'he top of erably composed of thin metal so that the rate of heat conduction between the inner and outer walls is slow. For some purposes the top of the inner tube I4 where it joins the ring 38 can be of reduced thickness as illustrated by the numeral 34, Fig. 3, whereby to increase the length of the high resistance thermally conducting path between the shells. 'Ihe ring 3D is sufficiently. rigid ordinarily to maintain the inner and outer receptacles in spaced relation free from contact so that no other spacing means is rendered necessary.

The bottom closure for the outer receptacle is provided with an upturned neck 36 in which a plug 38 is welded, the plug having a screw-threaded portion 48 for connection with a vacuum pump and having a passage 42 therethrough by which the space 24 can be evacuated. The passage 42 can be closed by a screw-threaded valve 44 prior to the disconnection of the plug from the vacuum pump whereby to seal off the space 24. The screw-threaded val/ve 44 can then be permanently sealed by solderin/g. The bottom face 0f the disc I6 of the inner receptacle is provided with arecess 46 adapted to receive a locating tool that centers the inner receptacle with the outer receptacle durin/g the process of welding the two lreceptacles a /d the ring 30 together. The outer receptacle is e closed within and intimately connected with a non-metallic heat-insulating shell composed of bakelite or other artificial resin 48. Preferably the shell comprises cIa. tube. 50 which has a separate bottom closing disc 52 of the same composition cemented therein, and the shell is cemented to the outer metal shell 22. The shell- 'nected with the outer lnsmanng sneu so and said sist impacts and the pressure of the atmosphere and thereby to support the thin metal shell. Thus the insulating shell constitutes the pressure-resisting shell and the metal shell in effect constitutes an imperforate lining or seal for the insulating shell. The metal and insulating shells may be intimately connected by a suitable cement or the insulating shell may be built up on the metal shell by a moulding process, using, for instance, a dry phenol condensation powder, or by coating the metal shell with a liquid solution of the insulating material.

The container is provided with a heat-insulating cap 54l which preferably is removably screwthreaded to the' container. In the modification illustrated in Fig. 2, the outer shell 22 is provided with an outstanding continuous flange 62 which is in line with the top of the inner container and said flange has an upstanding annular internally 20 cemented to the screw threads 64 and also to the 25 top of the shell 48. In the construction illustrated in Fig. 1 the topof the outer shell I2 is -provdcd with an outstanding continuous flange 68 that is seated against the top of the heat insulating shell 48 and an internally screw-threaded ring 10 of heat insulating material is cemented to the top of the shell 48 and receives the cap 54.

A resilient packing washer 12 is located under the cap 54 and on top of the inner and outer receptacles to seal the joint therebetween. The cap 54 is provided with a reduced internallyscrew-threaded passage in which the screwthreaded closure or cover 14 is removably located. When a liquid is in the inner container it is su'icient merely to remove the cover 14 to pour out the liquid. When the inner container contains solid masses the cap 54 can be removed to permit the introduction or removalv of the solid masses. The inner face of the cap 54 is provided with a hollow evacuated ring 16 which has\a polished heat reflecting inner surface and is adapted to retard the transmission of heat from the interior of the container through the cap.- Sad disc has a passage 18 in the middle thereof through which communication can be established flecting surface which overlies the opening 18 and 60 bears against a resilient washer 84 which overlies the upper face of said disc 16. The lower portion of the insulating shell 48 is provided with external screw threads 86 which conform to the screw threads 58 of the cap 54 so that the screw 65 threads 86 of one container can be screw-threaded into the top 'of a second container,'thereby to form in eiect a single container of double l'the capacity and wherein the bottom 52 of one container forms a top closure for the other. The upper container may contain a liquid while the lower container mayl contain solids. The bottom screw threads 86 alsol constitute means by which the container can be secured freely to some convenient support.

. lar to the flange 68 of Fig. 1.

While the assembled meta-l walls may be assembled, as shown, with abutting or face contact, they may be preliminarily united instead by crimping the adjacent edges, in ausual manner, thesealing metal entering the capillary space between the crimped walls; or the walls may be'welded together electrically or otherwise prior to the sealing step.

The present invention also comprehends a vacuum insulated extension 94, see especially Fig. 5. Said extension comprises an inner metal tube 9'6 having a straight side wall and substantially the same diameter as the diameter of the inner receptacle I0. A straight walled outer metal shell 98 surrounds the tube 96 and is spaced therefrom to provide an evacuated heat insulated space therebetween. The bottom of the outer tube 98 is provided with a reduced neck |02 which surrounds and contacts and is welded or alloyed to the inner tube 96. The upper end of the tube 98 is provided with an outstanding flange |04 simi- 'I'he upper portions of the inner and outer shells are Welded to the interposed spacing and connecting ring |06 similar to the ring 30 of Fig. 1. A heat insulating shell |08 similar to the shell 48 surrounds the outer shell 98 and is provided at the top with the internal screw threads |||i and at the bottom with the external screw threads ||2. The screw threads ||2 are adapted to be screw-threaded into thev screw threads at the top of the container and the cap 54 of the container is adapted to be l screw-threaded into the screw threads ||0 so that the extension and the container are assembled as stated, and the effect produced is that of a single container of increased length. The construction of the extension can otherwise be as described in connection with the Vpreviously described container.

The diagrams Figs. 6 to 11 illustrate the principles of thc method and steps in the preferred embodiment of the present invention. Fig. 6 shows tlie wall assemblage 9, constituting the. vacuum chamber before sealing and uniting the walls and evacuating the chamber space '24. The inner and outer tubular walls |4y and 22 are spaced apart concentrically. At the bottom Athe inner wall is closed by.disk I6 while the outer wall is closed below by the cupped bottom piece 26, the outer flange 28 of which has face contactwith the cylindrical wall. At the top between the tubes or cylinders is the metal ring 30 having depending flanges 32. The bottom 26 has the central flange 36 in which is set the port piece or open plug 38 having cuter threads 40 for coupling the exhausting apparatus. and an open passage 42 through it, to be closed by a plug 44 shown in Fig. 1.

'I 'his assemblage of walls, preliminarily secured by pressure or otherwise, is to be permanently sealed as described, and united at the joints. which may present abutting or face contact or crimping attachment, in any case involving crevices of capillary proportions.

The next diagram Fig. '7 shows enlarged portions of walls I 4 and I6 assembled, with a capillary joint between them, but before any treatment. Fig. 8 shows the same walls I4 and I6, for example ot iron, but with an application or distribution of copper, as a layer, or in spots, or otherwise, and inside, outside or both, as already described.

Fig. 9 diagrammaticallyillustrates the step of heating'ii a reducing or hydrogen atmosphere. A series of the Wall assemblages 9 is shown carried through the heating chamber A on a suitable conveyor B, the port piece 38 being open at this stage. The chamber A is conventionally shown y as heated by electric coils C having exterior terminais D. The conveyor carries each assemblage slowly through the heating chamber, to give it the requisite period of exposure to the specified temperature, at orfabove the melting point of copper, so that the applied copper is caused to melt and flow wetly as described. From the heating chamber each product passes preferably into 10 a cooling chamber E in which are enclosed conduits F to carry cooling fluid. Curtains G as of asbestos are indicated at each of the walls covering the entrance and exit of each chamber. Hydrogen or other reducing gas may be continuously l5 supplied to the heating chamber or furnace by pipe H, passing thence into and from the cooling chamber. This gas chemically cleans the iron walls at and below the surface, and prevents oxidation. The resulting condition of each wall surface when passing from the heating chamber is indicated approximately in the diagram Fig. 10 wherein, highly magnified-the copper is shown as substantially covering the surface of the iron, and entering also to a substantial depth into every passage and pore existing between or in the minute crystalline particles, the copper flowing freely over the surface in a w`et condition and being drawn into the surface by the alloying attraction of the iron for the copper, or by capillary attraction of the ne passages for the fluid metal, or both; in some cases this action being so complete that the copper may pass clear through a thin wall and show at the opposite side. Fig. 11 shows the product of these steps, the coppernow forming a sealing coating or film I8, and the surplus copper adjacent the corner having been drawn into the joint between the contacting walls 4 and I6 and effected a permanent 40 and tight bonding and uniting thereof. If a reflecting surface is desired a chromium Vplate layer 20 may be applied on top of the copper, as shown in Fig. 4, copper being well adapted to the adherence of chromium. 15

Following the sealing and uniting of the walls the chambers are subjected to usual exhausting steps, not shown, at the completion of which the port or passage 42 is closed by plug 44 and solder applied to the plug for a nal sealing.

The product of this invention may be summarized in one aspect as a gas-impermeable metal-walled vacuum chamber, having for example the form of a container, the same com-- prising 'the-metal walls, as `of iron, arranged to 55 form andI completely enclose an evacuated space, with a permanentlystopped exhaust port; and upon said metal walls a sealing coating of a metal as copper, which has a lower melting point than the wallA metal and has an alloying attraction therewith, part of said sealing metal being in an indrawn position (caused by the alloying attraction or by capillarity or both at a temperature between the melting point of the' two metals) thereby occupying and closing the permeable pores and passages of the walls and sealing them gas-tight. The walls being preferably connected by joints such joints are bonded by the entry of the sealing metal into the crevlces thereof. In j the aspect of method the invention may be described as the process of manufacturing such a product comprising arranging the metal walls to surround completely the space within the chamber, but leaving a temporary gas port, applying upon the wall'surface. in any of the ways de- 75 scribed, a sealing metal of substantially lower melting point than the wall metal and having an alloying attraction therewith, then heating the chamber in a reducing atmosphere to a-sealing temperature sufiiciently above the melting point of the sealing metal to cause it to flow wetly upon the hot wall surfaces and to enter into and close and occupy, by capillarity or alloying attraction, or both, the permeable pores and passages of the Wall metal, allowing the wall to cool to solidify the sealing metal, and thereafter evacuating the chamber'space and stopping the gas port to close permanently the space. The assembling of the walls preferably precedes the sealing thereof, and any wall joints are preferably bonded in the same operation with the sealing.

The vacuum chamber of this invention is shown illustratively as adapted -for heat-insulating purposes. for which it is of special advantage. The walls are of sheet metal or steel which is light or thin, of the order of 0.10 inch or less, down to a fraction thereof; as stated thewall metal is of a thinness subject to crimping for uniting the wall parts, and may sometimes even be so thin as to require reinforcing against collapse; the product being light and perhaps portable, as is the vacuum bottle described. Such character of walls tends to impair the gas tightness of untreated walls. In the preferred process the nal forming or assembling of the wall parts in their permanent relation precedes the heating treatment for wall sealing, which is important, and the assembling may also precede the application of the copper or sealing metal to the walls, which is of less,

importance. The finished chamber walls completely enclose the evacuated space without need of packing or clamping devices. l

I claim: 1. The process of manufacturing a highly gas-f impermeable metal-'walled vacuuml chamber,

comprising arranging the wall metal to form and Vcompletely enclose the chamber, leaving, an exf haust port, then applyingupon the chamber wall' surfaces a sealing metal of substantially lower melting point than the wall metal and having an alloying attraction therewith, then heating the chamber in a non-oxidizing atmosphere to a sealingtemperature sufficiently above the melting point of the sealing metal to cause it to flow wetly upon the hot wall surfaces andto be drawn bemetal walls to form the chamber, leaving an exhaust port in one of the walls, and, applying upon the wall surfaces a sealing metal of substantially lower melting point than the wall metal and having an alloying attraction therewith, and the subsequent steps of heating the chamber in .a reducing `atmosphere to a sealing temperature suilicientlyv above the ,melting pointof the sealing metal to cause it to flow wetly upon the hot wall surfaces and to enter into and closethe permeable pores and passages of the wall metal, followed by allowing the wall to' cool-to solidify the sealing metal, and thereafter evacuating the chamber and stoppingl the exhaust port.

' 3. The' prbcess of manufacturing a gas-im-` permeable beateinsulating metal-walled vacuum chamber, comprising-arranging sheet-iron walls to form the chamber, leaving an exhaust port, then applying upon the wall surfaces a sealing metal as copper of substantially lower melting-point than the wall metal and having an alloying attraction therewith, then heating the chamber 5 in a hydrogen reducing atmosphere to a sealing temperature sufiiciently above the melting point of the sealing metal to cause it to now wetly upon the hot wall surfaces and to enter and close the permeable pores and passages of the wall metal, i0 allowing the wall to cool to solidify the sealing metal, and thereafter evacuating the chamber and stopping the exhaust port. 4. 'I'he process as in claim 2 and wherein the wall metal is. iron, and the sealing metal is copper, 15

and the sealing metal in fully divided form is first mixed with a volatilizable vehicle, as pyroxylin, and applied or distributed upon the wall surfaces before heating.

5. The process of manufacturing a gas-im- 20 permeable metalwalled vacuum chamber, comprising the preliminary steps'of assembling sheet metal'wall parts in final relation to form and enclose the chamber, leaving an exhaust port, the said parts meeting at vjoints presenting crevices of 25 capillary thinness, and applying upon the wall surfaces a sealing metal` of substantially lower melting point than the wall metal and having an alloying attraction therewith, and applying the sealing metal also at such joints in substantial 30 quantity, and the subsequent steps of heating the chamber in a reducing; atmosphere to a sealing temperaturefsu'lciently,above the melting point vof the` sealing metal to cause it to ow wetly uponthe hot'wall surfaces and to be drawn 35 into and-close the permeable pores and passages l of the V`wall metal, and at the Sametime to enter also thefcrevices at the joints and bedrawn into and-unite with the wall metal bounding such crevices, and then allowing the wall to cool to^40 solidify the sealing metal, thereby to seal the ,wall surfaces, and at the same time to seal the crevices between the wall parts and permanently t bond such joints,'and thereafter evacuating the chamber and stopping the exhaust port.` 45 6. The process of manufacturing a gas-impermeable metal walled vacuum chamber, comprising assembling sheet iron wall parts to form the chamber, `leaving an exhaust port, the said parts meeting at joints presenting crevices of 50 capillary thinness, then applying copper upon the wall surfaces and also at such joints in substantial quantity, then heating vthe chamber in a reducing atmosphere, as hydrogen, to a rsealing temperature suiliciently above the melting point 55 of the copper to cause lt to fiow wetly upon the hot iron` wall surfaces' and to be drawn into and close the permeable pores and passages of the walls, and at the Sametime to enter also the crevices at the joints and be. drawn into and unite 50 with the wall metal contiguous to such crevices, and allowing the wall to cool to solidify the copper, thereby to seal the wall surfaces, and at the same time to seal the crevices between the wall parts and permanently to bond such joints, and 65 thereafter evacuating the chamber and stopping the exhaust port. v

7. The process of manufacturing a metal walled lvacuum insulated container; comprising arranging spaced metal"vvalls, as of fr on, to form the 70 container and to enclose a vacuum space between the walls, leaving an exhaust port, and applying g upon the wall surfaces and at the joints between wall parts a sealing metal, as of copper, of substantially lower melting point than the wall metal 75 'larity the permeable pores and passages of thev Wall metal, and at the same time to enter the 'joints between the wall parts, and allowing the ythe permeable pores and passages of the wall metal, and at the same time to enter between the wall parts-at the joints, and allowing the wall to cool to solidify the sealing metal thereby to seal the wall surfaces and to bond the joints, and finally evacuating the chamber and stopping the exhaust port.

8. 'I'he process of manufacturing a gas-tight heat insulating metal Walled vacuum chamber, comprising assembling in final relation the metal walls to surround completely' the space within the chamber, but leaving a temporary lgas port, and applying upon the wall surfaces a sealing metal of substantially lower melting point' than the wall metal and having an alloying attraction therewith, and thereafter heating the assembled chamber in a reducing atmosphere to a sealing temperature sumciently above the melting point of,

the sealing metal toI cause it to flow Wetlyupcn the hot wall surfaces and to enter into and close and occupy by attraction or capillarlty the per-o meable pores and passages of the wall metal, allowing the wall to cool to solidify the sealing metal, and thereaften evacuating the chamber and stopping'the gas port to close permanently the space within the chamber.

9. The process of manufacturing a gas-tight metal walled vacuum chamber, comprising the preliminary steps of assembling sheet metal wall pants' to surround the space within the chamber,

wall to cool to solidify` the sealing metal, thereby to seal the wall surface and at the same time to" l bond permanently the joints, and thereafter evacuating the chamber andpermanently stopping the exhaust port.

10. The process of manufacturing a gas-tight y metalwalled vacuum chamber of light or portable nature having walls of light sheet-metal as iron and-with an evacuation port in a'wall, said process, comprising applying upon the surface of the wall metal a. sealing metal of substantially lower melting point than the wall metal and having an'alloying attraction therewith, then heating in a non-oxidizing or reducing atmosphere to a sealing temperature sufficiently above the melting point of the sealing metal to cause it to flow wetly upon lthe hot wall surfaces and to enter into and close and occupy by-attraction or c'apillarity the permeable pores and passages of the wall metal, allowing the Walls to cool to solidify the sealing metal, and thereafter evacuating the completed chamber and permanently stopping the Dort of evacuation to close and seal the vacuum space within the chamber.

11. A gas-tight metal-walled vacuum chamber of light or portable nature, comprising sheetmetal walls as of iron arranged to form and enclose the evacuated space and in one of the walls a. permanently stopped exhaust port; said metal Walls being sealed to a highly gas-impermeable conditionl by an application thereto of a sealing metal, as copper, having a lower melting point than the Wall metal and having an alloying attraction therewith, some of said applied sealing metal existing in a position below the surface of the wall metal, and occupying to an appreciable 1 depth and molecularly closing the permeable pores and passages of the walls thus rendering the walls gas-impermeable and the chamber gasti'ght; said sealing metal having been indrawn to such position, as by capillary attraction and wet penetration, at a temperature between the melting points of the two metals in a non-oxidizing atmosphere.

12. A vacuum chamber as in claim 11 and wherein the chamber walls comprise assembled wall parts in close contiguity at vthe joints, and with portions of the wall sealing metal occupying and bonding such joints and rendering them gastight.

13. A vacuum-insulated container comprising inner and outer vessel Wallsy as-1of sheet-iron spaced apart to enclose an evacuated space between them, with a permanently stopped exhaust port in one of such Walls; said metal vessel walls being sealed to a highly gas-impermeable condition by an application thereto of a sealing metal, as copper, having a lower melting point than the Wall metal and having an' alloying attraction therewith, some of said sealing metal existing in a position below the surface of the wall metal, and

occupying to an appreciable depth and molecularly closing the permeable pores and passages of the walls thus rendering the walls gas-impermeable and the container space gas-tight; said sealing metal having been indrawn to such position,- as by capillary attraction and wet penetration, at a temperature between the melting points of the two metals in a non-oxidizing atmosphere. 14. A vacuum-insulated container as in claim 13 and wherein the sealing metal is copper, and some of such copper substantially covers the Walls, and such copper covering being exposed in uncoated condition.

Y EUGENE L. SCHELLENS.

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