US 3713930 A
The process concerns the realization of elements comprising sealed cavities filled with pressurized gas. Said process consists in arranging, in a pressurized chamber, sheets of plastic material; in forming, in at least one of said sheets, cavities which are filled with said pressurized gas; in closing and sealing said sheets according to a closed outline, in such a way as to form one or several closed cavities which, being situated in an ambient with normal pressure (atmospheric pressure) permits the expansion of the gas contained in said cavity or cavities.
Description (OCR text may contain errors)
United States Patent 91 Levrini et a1.
 PROCESS TO FORM ELEMENTS UNDER PRESSURE  Inventors: Tullio Levrini, Via Turati 26, Milan; Giuseppe Corti, Casana, Como, both of Italy  Filed: April 16, 1970  Appl. No.: 29,007
 Foreign Application Priority Data April 15, 1569 "iiiyu'gnfji .Q'. 1 5855/69  References Cited UNITED STATES PATENTS 2,621,139 12/1952 Messing ..161/120 3,303,243 2/1967 Hughes et a1 ..264/22 3,503,825 3/1970 Moore ....l56/245 3,523,055 8/1970 Lemelson ..161/43 3,575,757 4/1971 Smith ..156/147 3,619,442 11/1971 Henderson r 264/89 3,660,189 5/1972 Troy, ..156/145 2,579,044 12/1951 Kober ..156/285 X 3,142,599 7/1964 Chavannes ..156/285 X 3,322,598 5/1967 Marks et a1 ..156/285 X 3,366,523 1/1968 Weber ..156/285 X 3,586,588 6/1971 Solbeck.... ..156/285 2,495,124 1/1950 Morner ..297/D1G. 3 3,113,788 12/1963 Johnston ..297/D1G. 3 3,226,285 12/1965 louenko ..297/452 X 3,495,874 2/1970 Dean ..297/462 UX Primary ExaminerRobert F. Burnett Assistant Examiner-Robert A. Dawson Att0rney-Woodhams, Blanchard & Flynn  ABSTRACT The process concerns the realization of elements comprising sealed cavities filled with pressurized gas. Said process consists in arranging, in a pressurized chamber, sheets of plastic material; in forming, in at least one of said sheets, cavities which are filled with said pressurized gas; in closing and sealing said sheets according to a closed outline, in such a way as to form one or several closed cavities which, being situated in an ambient with normal pressure (atmospheric pressure) permits the expansion of the gas contained in said cavity or cavities.
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A y Y 15 5 /5 PROCESS TO FORM ELEMENTS UNDER PRESSURE The present application concerns a process to realize elements under pressure and the elements obtained by means of said process.
The process according to the invention is substantially characterized in that one or more intermediate areas of gas are left between at least two plates, at least one of which is made of flexible and/or elastic, gasproof material whereafter said areas are soldered together and/or peripherially cut, whereby such operations are carried out under an ambient pressure which is higher than the atmospheric pressure, in such a way that, in a normal ambient (atmospheric pressure) an expansion of the gas contained in said areas is realized in order to form one or several housings, in accordance with the features to be realized.
The invention will now be described with reference to the attached schematic drawing, which is submitted for indicative purposes only, without limiting the scope of this invention.
FIG. 1 shows a longitudinal section of a device designed to perform the process;
FIGS. 2A through 2L are plan views of several embodiments of the realized element;
, FIGS. 3A through 3? show, in section, different forms of the realized element;
FIG. 4 is a close-up view, in longitudinal section, of the device to realize the single cells;
FIG. 5 is a close-up view, in longitudinalsection, of the device for continuous extraction;
FIG. 6 is a close-up view, in cross-section, of an apparatus provided with a device for intermittent extraction;
FIG. 7 is a close-up view, in transversal cross section,
of a device provided with fluidizing means;
FIG. 8 is a view, in transversal section, of an apparatus for loading the elements into a housing;
FIG. 9 shows, in partial section, an element formed with several single elements; I
FIG. 10 shows, in perspective, a profiled element formed with several single elements;
, FIG. 11 shows, in perspective, one continuous, profiled element.
With reference to FIG. 1, 1 shows a container capable of resisting the preselected internal pressure.
In the container two bobbins 2 and 3 are arranged, onto which the two sheets are wound Said two sheets, which are maintained at a certain, preselected distance from each other, for instance by means of two rollers 4 and 5, are conveyed between two working-rolls 6 and 7, at least one roll 6 of which is provided with profiles in relief 8 designed to execute, in co-operation with counter-roll 7, the soldering and/or cutting operation of the two sheets in accordance with the desired design. In the case of sheets made of thermoplastic material (such as polyethylene or the like), the soldering and cutting can be performed with heat (i.e. by heating at least the active parts 8 of roller 6). The distance between the two above mentioned sheets, at the intake of the working rollers 6,7 causes the enclosure of a certain quantity of gas inside such areas as are perimetrally soldered and/or cut.
If the soldering operation only is performed, the so obtained sheet can be wound onto a bobbin 9. The
described motion proceeds in the direction shown by arrows X. The operation is performed by maintaining in container 1, a preselected gas pressure (by means of a compressor 10 or by other means, for instance bombs of pressurized gas). After performance of the above mentioned operation, the pressure is relieved by opening cock 11, until said pressure descends to the atmosphericpressure and bobbin 9 can be removed, for utilization during a successive working cycle. During the step in which the pressure is relieved, bobbin 9 tends to assume a different shape, due to the progressive expansion of the gas containned in the cells. If, for certain requirements, such as, for instance, space requirements, transport, utilization etc., said expansion is undesirable (or should be limited), it is possible to retain the outer end of the bobbin-forming sheet; or otherwise to introduce said outer end into a tubular containing sheath; or otherwise to perform wrapping, binding and like operations, previous to proceeding with the decompressing operation.
The space between the two sheets, which is necessary to form the initial pressurized gas pockets (cells) can be obtained by means of different systems; for instance by:
introducing a layer of advantageous material between the two sheets, such as, for instance, a wire net, threads, sheets of spongy or expanded material, felt, fabric, and the like, showing the desired thickness (indicated with 12 in FIG. I, wound onto bobbin 13);
introducing a gas jet between the two sheets, to maintain said sheets at a certain distance one from each other (for instance, through conduit 14 or by making use of an internal fan);
creating, at least on one sheet, imprints to realize the initial pocket (by'cold or hot stamping, by pressure, underpressure or other known means);
creating, at least on one sheet, projections, swellings or the like to serve as spacers and pressurized gas containers (in this case the shape and the position of the projections refer in no way whichever to the shape and the position of the final pockets realized by means of rollers 7 and 8');
realizing, near roller 6 (and/or 7), a suction of the sheet in the direction of the above mentioned rollers (suction is obtained by contact between the sheets and the rollers through micro-holes shown by said rollers which communicate, like a lower pressure source, with the internal pressure, for instance with the atmospheric pressure);
providing a fixed thickness, such as a knife, wedge or the like (acting as a distance-piece of the sheets) between rollers 6 and 7.
In order to obtain particularly advantageous results the sheets can be more than two, for instance three or more, of any desired thickness and features.
To form the two above mentioned sheets, it is possible to start also from one single tubular element, to obtain an initial lateral closure of the two sheets. It is also possible to close or adhere the edges of said sheets initially to each other, using for this purpose two side elements (by means of rotating, heat-solderingknives) for continuous soldering.
FIGS. 2A through 2L show several possible solutions of formed sheets and cells in accordance with the invention, by using two sheets (and, if desired, a third,
flat, intermediate sheet). A shows longitudinal straight and parallel solderings; B continuous, straight, transverse solderings, C continuous crossed solderings, D diagonal, crossed solderings, E solderings forming circular areas (the gas is contained inside said circles), F solderings forming staggered, elongated areas, G diagonally staggered, elongated areas, H areas formed with two concentric circles (oval-shaped), L pyramidal areas. FIG. 3A shows a section along line Illa-Illa of FIG. 2A, of the sheet after expansion; FIG. 3B is a section along line lllb-lllb of FIG. 23 (after expansion); FIG. 3C is a section along line IlIc-IIIc of FIG. 2E; FIG. 3D is a section along line IIId-IIId of FIG. 2H; FIG. 3B is a section along line IlIe-llle of FIG. 2L; FIGS. 3F and 3G indicate, in cross section, pyramidal and hemispheric elements in which one of sheets is sufficiently stiff (for instance, due to its greater thickness) to prevent said sheet from deforming due to internal pressure during expansion; FIGS. 3H, 3L, 3M and 3N single elements (not connected to each other on the sheet) are shown in cross section, such elements having been obtained by means of a direct cutting operation during the soldering process or during a successive operation, such elements being, respectively spherical H, toroidal L, tubular M and twin-spherical N in shape; (the two spheres according to N can be severed by means of a successive cutting and soldering operation); in FIG. 3? one sheet 16 is sufficiently stiff to support the spherical elements 17 obtained by expansion from sheet coupled according to the scheme shown in FIG. 2E.
It can be easily understood that the shape of the soldered seam as well as that of the so-obtained elements can differ from each other, according to the different requirements which have to be met (for instance the execution of continuous, wave-shaped, or S-shaped, or criss-cross shaped soldered seams and the like).
It is obvious that it is possible to obtain the illustrated shapes by making use of one single workingroller pair 6, 7 or otherwise more roller pairs, each of which is designed to execute one soldered unit and/or one unit of cuttings. The gas, which is introduced into container 1, can be of different kinds, according to the result to be attained, such as, for instance air, nitrogen, hydrogen, helium, argon and the like.
FIG. 4 shows the realization, by means of rollers 6, 7', of single elements 18 (not in the form of sheets), which are dropped into container 19; the latter is capable of preventing the expansion of the elements when they, are returned to ambient pressure, in order to facilitate transport or storage or otherwise to permit certain uses or successive working steps.
In FIG. 5 container 1'' is provided, at one wall thereof, with two rollers 20, preferably provided with a peripheral elastic thickness, such rollers having the task to realize a seal between the inside and the outside of said container, to prevent gas leakage. Sheet 21 is conveyed between rollers 20, said sheet 21 being provided inside the container, as previously explained, the cells of which expand as soon as they reach the outer ambient, which has a lower pressure than the inner pressure of container 1". It is obvious that also the bobbins of initial sheets can be arranged outside the container, following, for this purpose, a like system.
FIG. 6 shows a container 1", provided with two removable, pressurized containers 23 and 24, into which elements 25 are dropped alternately. Acting alternately upon lock-gates 26 and 27 when one of containers 23,24 is filled, container 23 or 24 can be removed from flanged connection 28, without relieving the inner pressure thereof, nor the inner pressure of container 1", to substitute container 23(or 24) with another empty container while container 24 (or 23) which is being still filled, has not yet been removed. Therefore, it is possible to act continuously inside container 1".
The process claimed by the present invention enables performance of a drafting operation of the material during the decompression step, by heating, for this purpose advantageously the elements which have been already soldered and/or cut. For instance, it is possible to perform the entire decompressing operation after the heating of the elements to the desired temperature which is required to realize the desired, final shaping. On the other hand, it is also possible to first decompress and then to heat the elements. Finally, it is possible to decompress and to heat simultaneously, in accordance with a pro-selected cycle of pressures and temperatures. It should be borne in mind that expansion causes the gas to automatically absorb calories.
In a particularly interesting and advantageous working-cycle, the elements are heated, whereupon a partial decompression with simultaneous expansion and drafting of the material is performed, followed by a cooling down to a temperature at which the materials cannot be drafted, said working-cycles being completed by an expansion to the ambient pressure, in order to realize an advantageous elastic tension of the elements (with a residual inner pressure). As a matter of fact, a complete expansion by heat causes a partial collapse of the housing when the same is brought down to ambient temperature. It is, of course possible to select the cycle according to the nature of the materials, to the shape and dimension of the desired housings and to the requirements of the various end-users availing themselves of said cycle.
FIG. 7 shows part of the apparatus wherein the above described expanding and heating operation of the material can be performed. In said apparatus, a pressurized container 29 is provided with a lower gas inlet 30, to maintain the mass of elements 31 in suspension. Heating can be realized by means of irradiation (infrared rays), with hot gases, vapor or the like, whereas pressure can be set by means of valve 32. Cooling is obtained, either by changing the temperature of the entering gas, or by introducing cold gas or nebulized water into tube 33. If endless sheets have to be produced, the procedure followed for this purpose can be continuous, for instance by providing several chambers with different pressures and/or temperatures, said chambers being sealed, for instance according to a system shown in FIG. 5; or by making use of different means.
The initial or starting sheets can be also of different kinds of material, in order to obtain the desired results, for instance of elastomers, rubber, fiber-loaded plastic materials, rigid or semi-rigid panels, panels made of shavings, waterproof fabrics, paper, waterproof cardboard and so forth; or otherwise it is possible to make use of initial sheets with sheets or leaves of thermoplastic material adhered to the same.
In FIG. 8 pressurized tank 34 has therein a container 35 the upper part of which is open, inside of which there is an object to be wrapped packed or 'a filler 36. When locking gate 37 is opened, elements 39 are dropping down from hopper 38 into container 39, thus filling the gap between containers 35 and object 36. When the inner pressure is reduced by means of valve 40, elements 39 expand, thus putting the container and the object in tension, to realize a permanent, elastic wrapping. if it is desired to realize a unibloc closure, it can be obtained by sealing the upper elements, by spraying an adhesive (through tube 41).
It is further possible to solder all elements 39 to each other in the contact areas, by distributing an adhesive over the surfaces of said elements or by making use of heat. The adhesion of the above mentioned elements to each other (by means of an adhesive or by heat) can be realized either previous to expansion, during expansion or after complete expansion of such elements to the ambient pressure. it is thus possible to realize advantageous composite volumetric elements, such as, for instance, that shown in FlG. 9 parallelepiped profiled element), as well as single elements, for instance ball-shaped or like elements, or otherwise mixed elements of different shapes.
Profiled elements 42 can be contained in, or connected to outer sheets 43, sealed, or less, to each other along their peripherial edges 44.
it is thus possible to realize panels, mattresses, cushions, floats, tires or the like, having fair elastic sound-damping features and being good heat and acoustic insulators, etc.
The single elements, with or without outer sheaths, adhered or less to each other and/or to the sheath, can be realized previous to, during or after expansion. Such elements can be of different shape in order to suit several purposes, for instance the production of packing material, furniture, mattresses, protective elements or the like.
FIG. shows an armchair made of one single piece, realized in accordance with the present invention. It is further possible to produce quickly and easily continuous profiled elements, both compact or hollow, with the procedure according to the invention. FIG. 11 shows a tubular profile 45, made of single elements and providedwith a tubular outer sheath 46. Of course, the outer profile can be square, polygonal or other.
The outer housings or sheaths (such a shown in FIGS. 8, 9, l0 and 11) can be made of thermoplastic material, rubber, fabric, leather, paper-like material or other.
. It is understood that the details of the embodiment of the process and of the obtained elements, of the material used, the shapes of such'materials and their end-uses may vary, without departing from the present invention. in particular, the adhesion of the sheets at the perimeter of the area tobe pressurized can be obtained as well, by making use of advantageous adhesives or other appropriate means.
We claim: l. A process for forming articles having trapped gas pockets therein, comprising the steps of:
providing at least two plate-like members having mutually engageable surfaces, at least one of said plate-like members being ofa flexible material;
positioning said plate-like members within a working chamber having a first ambient pressure substantially greater than atmospheric pressure;
positioning said two plate-like members in substantially superimposed relationship for trapping some of the pressurized gas in said working chamber between said plate-like members; then maintaining said superimposed plate-like members within said working chamber and sealing said plate-like members together at selected locations while maintaining said first ambient pressure substantially greater than atmospheric pressure to result in formation of a plurality of closed spaces between said plate-like members containing trapped pressurized gases therein; and then exposing said sealingly connected plate-like members to a second ambient pressure which is sub stantially less than said first ambient pressure for causing the pressurized gases trapped within said spaces to expand to cause at least one of said platelike members to deform into a definite shape.
2. A process according to claim 1, wherein the sealingly'connected plate-like members are exposed to atmospheric pressure to cause expansion of the gases trapped within said spaces.
3. A process according to claim 1, comprising the further step of heating said plate-like members to a desired temperature after said plate-like members have been sealingly connected at the selected locations. 1
4. A process according to claim 3, wherein the heating step is performed after the sealingly connected plate-like members have been exposed to said second ambient pressure causing expansion of the gases within said spaces.
5. A process according to claim 3, wherein the heating step is performed simultaneously with the expansion of the gases within the closed spaces due to exposure of the sealingly connected plates to said second ambient pressure.
6. A process according to claim 1, further including the step of maintaining said superimposed first and second plate-like members a predetermined distance apart prior to scaling said members for enabling the pressurized gases to remain between the members. I
6. A process according to claim 6, wherein the distance between the plate-like members previous to sealing of the members is obtained by means of external positioning rollers.
8; A process according to claim 6, wherein the distance between the plate-like members is maintained by spacing means located between the members and located upstream of the location where the sealing step is performed.
9. A process according to claim 6, further including the step of introducing between said plate-like members a continuous layer of material for maintaining said members said distance apart prior to sealing of said' plates.
11. A process according to claim 6, further including the step of providing one of said plate-like members with projection means thereon for maintaining said members said predetermined distance apart.
12. A process according to claim 6, further including the step of directing a gaseous stream between said two plate-like members for maintaining said plate-like members said predetermined distance apart prior to feeding said plate-like members to the sealing location.
13. A process according to claim 1, further including the step of cutting said sealingly connected plate-like members into a plurality of individual elements with each element having at least one trapped gas pocket formed therein.
14. A process according to claim 13, further including the step of introducing a plurality of said elements into a rigid housing at a pressure greater than the atmospheric pressure, and then exposing the housing to atmospheric pressure for causing expansion of the elements within the housing due to the trapped gases contained within the pockets.
15. A process according to claim 3, including the steps of heating the sealingly-connected plate-like members to a temperature approximating the flow temperature of the material for causing partial expansion of the gases trapped within said spaces, then cooling said plate-like members to a temperature below said flow temperature, and then causing further expansion of the gases trapped within said spaces.
16. A process according to claim 1, characterized in that it is a continuous process carried out in a pressurized container and by means of rollers designed to unwind the initial. plate-like materials, as well as by means of rollers to wind the finished materials into plates.
17. A process according to claim 16, characterized in that one of the winding and unwinding rollers are situated at the exit of the pressurized container and provided with sealing means at such point where the materials are introduced to into the rollers.
18. A process according to claim 16 characterized in that the sealing is done by a pair of rollers at least one of which has shaped projections designed to obtain the desired shape and arrangement of the sealing areas.
19. A process according to claim 1, characterized in that the endless, finished material is conveyed into sealed chambers arranged in a row, each of said chambers having different pressures and/or temperatures, to realize a complete and continuous working cycle.
20. A process according to claim 1, characterized in that the so-obtained materials are alternately arranged inside two pressurized containers that correspond to the processing container, in such a way as to consent, with the aid of locking gates, the execution of a continuous manufacturing process, as well as the alternate removal of one of the filled containers and the substitution of the filled container, with a new, empty container.