US 3926306 A
A method for the manufacture of a closed casing, in which material is stored at a pressure of less than 10<->1 torr, characterized in that the casing is sealed in a space in which the pressure is at least equal to the pressure mentioned above.
Claims available in
Description (OCR text may contain errors)
United States Patent Van Nederveen 1451 Dec. 16, 1975 METHOD FOR SEALING A FILLED CONTAINER UNDER VACUUM, AND VACUUM-SEALED FILLED CONTAINERS Inventor: Hans Berti] Van Nederveen, Bosch en Duin, Netherlands Assignee: SKF Industrial Trading-and Development Company B.V., Jutphaas, Netherlands Filed: June 15, 1973 Appl. No.: 370,513
Foreign Application Priority Data June 28, 1972 Netherlands 7208731 us. (:1 206/84; 53/7; 53/22 R; 53/25; 53/86; l56/69; 156/73; 206/525 1m. cm B651) 81/00; 13653 31/02  Field of Search 53/48, 22 R, 53/24, 25; 206/84, 525; 156/69, 73, 272
 References Cited UNITED STATES PATENTS 2,806,595 9/1957 Spake 206/84 Primary Examiner-Travis S. McGehee Attorney, Agent, or Firm-Daniel M. Rosen  ABSTRACT A method for the manufacture of a closed casing, in which material is stored at a pressure of less than 10 torr, characterized in that the casing is sealed in a space in which the pressure is at least equal to the pressure mentioned above.
16 Claims, 5 Drawing Figures US. Patent US. Patent Dec. 16, 1975 Sheet 2 of2 3,926,306
i EH2 FiGa METHOD FOR SEALING A FILLEDCONTAINER UNDER VACUUM, AND VACUUM-SEALED FILLED CONTAINERS 1 BACKGROUND OF THE INVENTION The invention relates to a method of manufacturing a sealed casing in which material is stored at a pressure of I less than torr.
A method is known whereby objects are=.obtained which are particularly. suited ,for processing in an extruding device. These objects usually take the shape of a round bar, a tube or similar section, and comprise primarily a casing, called container, in which powdered or granular material is usually'stored, and a closure (lid). The material is made into a relatively dense mass by a compacting process, after which the container is evacuated, i.e. air and moisture'are withdrawn from the container until the pressure in the container hasreacheda value between 10 and 10". This method of removing air, moisture andsuch like substances has so far been effected with the aid of a tube connected to the container and to which a pumping installation is connected. After the desired pressure in the container has been reached with the aid of the pump, the connecting tube between the container and the'pumping installation is cut and sealed at the same time.
SUMMARY OF THE INVENTION;
The invention introduces a method'which considerably reduces the operations described in the-foregoing and used by the known method. The method in accordance with the invention is therefore characterised'in' that the casing is sealed in a space in which the pressure is at least equal to that mentioned above. The invention will be further explained by referenceto the drawing; advantages and other features will becomerevident from this.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammaticlview of a device provided with a space or chamber in which the methodis ap-' DESCRIPTION OF PREFERRED EMBODIMENT According to the view of FIG. 1 the-device (with which the method in accordance with the invention can preferably be applied) comprises a space or chamber la with a work table 2, comprising interconnected movable assembly tracks 3a, 3band 3c, onwhich containers 4a, 4b and 4c are placed. Assembly track 3a is connected with a compacting device 5, for example a vibrating mechanism. Content 6 (powdered or granular material or otherwisej is densified there to a compact mass 7 by the compacting device 5, The containers4b containing a compacted mass are thereupon passed on to track 3b, on which the actual;evacuating and sealing of the container take place, To this end,, space la is put under a pressure of 'at least 10 torr in, accordancev with the invention, which is effected with the aid ofan' air pump 8, the required pressure in space l a'b eiing maintained in conjunction with valve mechanisms 9a i and 9b. During evacuation of air, moisture and similar substances from containers 4b, these are surrounded by means 10, which ensure that the -densified masses 7 remain fixed or stabilized in the containers. In this embodiment, -means 10 consist of magnet coils, whose magnetic field is controllable; the strength is made dependent on the magnetic properties of the material 6,7 for instance. It is evident that other means for fixing or stabilizing the material, such as a suction device or other known mechanical fixing devices, can be used. Thereupon each container 4b issealed at least'on one side by means of a specific sealing device, for which the cathode 13 with control electrode 14, and an anode 15 at some distance from it. At the lower end of column l'la an electromagnetic focusing lens 16 as well as beam-deflection coils 17 are fitted. Column 11a fur- .thermore carries a reading an inspection viewer 18a with mirrors 18, with the aid of which the strength and direction of welding beam 19 can be influenced. With the device described in the foregoing a sharp, very accurately operating welding beam can be obtained, which can be controlled outside the device and which is. capable of favorably and quickly sealing the evacuated container. It will be clear that this welding. method, particularly because the welding takes place in a vacuum chamber and further because a welding beam controllable inevery respect is applied, offers considerable advantages, especially if the container to be sealed has a geometrically intricate shape.
The method in accordance with .the invention also has the advantage that-the number of rejects among the containers to be extrudedis very small. With con- =tainers made in accordance by the known method,
wherebyv it is necessary to cut the tube connecting the pump and container and seal it, leakages arenorare occurrence, but thiseffect is.very slight in containers manufactured in accordance with the invention.
Subsequently, aftersealing of one or more sides of the container, the latter is fed on to belt 30, after normal pressure has'been reached in space 1a throughcontrol of valve mechanism 9, container 4c is carried from the space, if necessary directly to anextruding device (not. further shown). I 1
In accordance with the invention, the sealing of a container4a is advantageously effected through the filled material itself functioning as sealing material.
FIG. 2a represents the longitudinal, section through a container 20 which comprises a casing 21 made of relatively thin metal, in which a powderedor granular material 22 is stored. It is observed that the casing need not specially be made of metal; a plastic material, for instance, (P.V.C.) with sufficient hardness with respect to the processing temperatures: concerned is likewise suitable as casing material or container. In this embodiment, container 20 is filled up to the edge of the container wall with the powdered orgranular material after the compaction process- In accordance with the inventidnthe upper layer 23 of material 22-is caused to melt with the aid of welding beam :19, in such a way that this melted layer is fused with the upper edge 21a of the container intoa seal 25 (FIG, 2b). This sealed container comprises a generally flat top surface .withno projecting parts, i.e. an unobstructed surface. It will be clear that in this embodiment the granular or powdered material 22 is particularly suited to shape a well-sealing fused layer. It will furthermore be clear that with the aid of the device in accordance with the invention the seal need not be formed especially at the upper edge, but that the formation of the seal can also be effected at a different level.
FIG. 3a represents a container 26, whose contents 27 consist of a non-meltable, at least not readily meltable substance. Generally, this consists of a filling material not suitable as sealing material for the container, as well as material which is difficult to check as to complete air-tightness or which is not reliable in this respect. A favorable solution in accordance with the invention is characterised in that after the compacting process and the evacuation at the top of the compacted mass 27, a readily meltable layer 28 to be fused with the wall of the container is provided, which is fused with upper edge 26a to form seal 29 (see FIG. 3b).
It is observed that filling a container in vacuum chamber 1a has the advantage of (powdered or granular) material not being lost but being always reusable on account of the specific conditions in the chamber. Furthermore, it is observed that the upper layer 28 (FIG. 3a), for instance, may have the same chemical composition as the actual filling material, but then has different physical properties to aid effective sealing. Contents 27 of container 26 may consist of powdered material, for instance, and the upper layer 28, serving as sealant, of granular material, with otherwise the same properties as the filling material. Also the layer to be fused may be substantially the same material as the casing.
FIG. 4a shows a longitudinal section through an extrudable container 30, whose contents, instead of granular or powdered material, consists of tablets 31. The tablets, which are usually made of powdered material possess in themselves a greater density than the basic material, so that the treatment of compacting the contents of a container can be dispensed with, or at least need be less intensive than in the case where only powdered or granular material is used. In this preferred embodiment a layer 32 of the top tablet is fused with the edge of container 30 by means of welding beam 19, so that an (air-tight) seal 33 (see FIG. 4b) is obtained. It will be clear that the entire tablet 31 can also be melted into a seal. If, however, the tablet material is not suited for fusing with the edge 30a of casing 30 the top tablet 34 (see FIG. 40) is provided, in accordance with a favorable embodiment, with a suitable layer 35 which is then fused with the edge 30a of container 30 to form seal 33 (see FIG. 4b).
FIG. gives a diagrammatic view of an embodiment of a welding device 36, with the aid of which the terminal parts 37 and 38 of the container can be sealed. In this embodiment the filling material 40 is readily weldable, at least there is readily weldable material near the terminal parts 37 and'38 of container 39. Briefly, this specific sealing device 36 works as follows: relatively heavy discs 36a and 36b made of specially suited material rotate at high speed in the vacuum space and at the same time move in the direction indicated by arrows p, i.e. perpendicularly to the center line of container 39. Where the container wall 39 and fusible layers 37 and 38 meet an intensive exchange of energy takes place, in
such a way that these layers and the terminal edges of container 39 are fused into seals4l (see FIG. 5b). This 4 welding method has the advantage of being economical as regards initial expenditure and maintenance, while it can also be favorably be effected into a space where the pressure is at least 10 by a method controllable from outside.
I claim 1. A closed and sealed container containing a stored material at a pressure less than 10' torr within said container, the container comprising a plurality of walls which surround and define an enclosure, one of said walls comprising a solid and generally flat outer layer of said stored material fused and sealed to adjacent walls of said remaining walls.
2. A method for closing and sealing a container which contains a material therein to be stored at a pres sure less than 10 torr, said container formed by walls having edges which define an opening of the container to be closed and sealed, and said material therein having a top layer adjacent said opening, the method comprising the steps of placing said container with said material therein in a chamber, reducing the pressure within said chamber to less than 10 torr and, while at said pressure, fusing and subsequently solidifying said top layer of the material thus forming said layer into a top wall of said container, and fusing said top wall of said edges to close and seal said opening.
3. A method according to claim 2 wherein fusing said top layer comprises directing onto said top layer the beam of an electron beam welding device which is within said chamber and operating under said pressure of less than 10 torr.
4. A method according to claim 2 wherein said material comprises a fusible substance as said top layer thereof and a non-fusible substance as the remainder below said top layer.
5. A method according to claim 2 wherein said top layer has substantially the same composition as said container.
6. A method according to claim 2 wherein said container has at least one additional opening similar to said first opening, comprising the further steps of closing and sealing said additional opening similarly to said first opening. I
7. A method according to claim 2 wherein said material is present in powdered form.
8. A method according to claim 7 comprising the further step of fixing said powdered material in said container prior to said fusing of same.
9. A method according to claim 8 wherein said material is magnetizable, and wherein fixing said material comprises applying a magnetic field thereto.
10. A method according to claim 2 comprising the further step of forming said material into tablet-shaped elements prior to placing same in said container.
11. A method according to claim 7 comprising the further step of vibrating said container and material therein prior to said fusing.
12. A method according to claim 2 wherein said fusing comprises directing a laser beam onto said top layer.
13. A method according to claim 2 wherein said fusing comprises providing heat with a friction welding device.
14. A closed container sealed according to the method of claim 2, and containing a stored material at a pressure within said container less than 10 torr, said container comprising a plurality of walls which surround and define an enclosure, one of said walls comprising said fused top layer of said stored material, said top layer being generally flat and unobstructed and sealed to adjacent walls of said remaining walls.
15. A closed container according to claim 14 wherein 16. A closed container according to claim 14 wherein said stored material comprises a fusible substance as said top layer thereof and a non-fusible substance as said top layer and said container comprise substantially 5 the remainder below Said p y UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 926, 306
DATED December 16, 1975 INVENTOR(S) Hans Bertil Van Nederveen it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
The Priority Document date should be --June 26, l972--.
Column 1, line 33, after "and" insert -as-.
Column 4, line 3, after "favorably" delete "be";
line 25, after "said top wall" delete "of" and substitute to--.
Signed and Sealed this Alien.
RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPatents and Trademarks