Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Patent
1986-06-16
1989-02-14
McCamish, Marion C.
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
264572, 4254051, 428 64, 428 66, 428 69, 428 76, 428178, 428192, 428194, 428349, 428458, 428483, 428 359, B32B 2302
Patent
active
048045659
DESCRIPTION:
BRIEF SUMMARY
This invention relates to pads for absorbing pressure shocks and a method of manufacturing same and relates in particular though not exclusively to pads and apparatus of the type described in relation to our earlier Letters Patent Application No. W084/00797 having an international publication date of the Mar. 1st, 1984.
Pads of this nature require to be such that they can for instance be connected to a water supply system without in any way forming means which could contaminate the water of the system.
It should be realized that the construction of such pads naturally presents problems because the pressure involved can be high and the pads for instance, in the case where they are used to prevent water hammer, may be subject to long periods of high alternating stresses and must be capable of withstanding such usage.
An object of the present invention is to provide a specific form of pad and pad arrangement which not only supplies durable pads but guards against contamination of the medium in which the pads are used.
A further object is to ensure that the membranes themselves, particularly a metal strength member, are not attacked by the fluid in which the pads operate.
A still further object of the invention is to ensure that the pads are held in a position where they effectively absorb pressure shocks.
A further object is to provide an effective method and machine for manufacturing such pads.
The pads according to this invention comprise a pair of laminates which are peripherally sealed together to contain a gas under pressure, characterized by the laminates each comprising a strength member impervious to gas in the nature of a foil, and on each side of the strength member, bonded thereto, thermoplastic films, further characterized in that the thermoplastic films, extends beyond the edge of the strength member, and the films are sealed together marginally beyond the edge of the strength member, whereby to totally enclose the strength member.
An added film can be bonded between the strength member and the thermoplastic film, and the method of construction of the pad can comprise forming a laminate having thermoplastic films bonded to each side of a foil strength member, placing a first such laminate adjacent to a second such laminate and heat sealing the ribbons together inwards of the periphery of the pad, cutting the pad from the laminates, and subsequently heat sealing the peripheral portions of the thermoplastic films together while allowing the softened thermoplastic films to flow to beyond the periphery of the strength member.
Construction can of course be varied but to enable the invention to be fully appreciated, an embodiment of such a pad and a machine for its manufacture will now be described with reference to the accompanying drawings in which:
FIG. 1 is a flow diagram showing the method of production,
FIG. 2 is a sectional elevation showing a pad assembly,
FIG. 3 is an enlarged sectional view showing an edge portion of a pad showing a preferred laminate assembly and showing by arrows how, at a first stage, the various layers are heat sealed together adjacent to the margin of a pad,
FIG. 4 is a view similar to FIG. 3 but showing by arrows how the actual marginal portion is heat sealed at a second stage to cause the thermoplastic layer to over-flow, the marginal edge of the metallic strength member,
FIG. 5 is a transverse section of the pad-forming part of the machine showing how two laminates are brought together and a pad is formed by blowing the laminates into dies and are heat sealed and cut, the seal being that shown in FIG. 3,
FIG. 6 shows in similar section how the partly completed pad is discharged,
FIG. 7 shows how the pad has its marginal edge sealed as shown in FIG. 4,
FIG. 8 places in central section how a series of such pads are joined together in readiness to be compressed into a container, and
FIG. 9 is a sectional end elevation of FIG. 8.
The laminates 1 and 2 which form the pad 3 as shown in FIGS. 2, 3 and 4 are of circular form sealed together around the perimeter 4 of the lamin
REFERENCES:
patent: 3442293 (1969-05-01), Erdmann
patent: 4117061 (1978-09-01), Vester
patent: 4238263 (1980-12-01), LoMaglio
patent: 4424182 (1984-01-01), Cerny
patent: 4497388 (1985-02-01), Dexter
WO 84/00797, Mar. 1984, International Application, Rast.
WO 81/00230, Feb. 1981, International Application, McHenry.
Adams Bruce L.
McCamish Marion C.
W. Rast Pty. Ltd.
Wilks Van C.
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