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(11) | EP 0 179 950 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improvements relating to sealing arrangements |
| (57) The invention provides a sealing member in the form of a plate (12) with an aperture
(16) therein, and a flexible diaphragm (14) partially overlying the aperture (16).
The diaphragm (14) has an aperture through which a tube or pipe can be passed so as
to stretch the diaphragm (14) so that it will seal around the pipe. Specifically the
sealing member is a top plate (12) for a vacuum cleaner dust bag, the apertures being
for receiving an inlet pipe of the vacuum cleaner which draws air through the dust
bag for the filtering of same. The sealing member is provided with the diaphragm (14),
applying a material such as a rubber latex which is in fluent condition to provide
a ring of the fluent material which overlaps the plate and portion of the aperture
(16). Whilst in this condition the ring material is cured to form a top flexible diaphragm
(14). The rubber latex or the like may be in liquid form and may be applied by dripping
the material from a head which overlies the plate (12) aperture (16) and an insert
therein, and by rotating the head so that the drips when they fall onto the plate
(12) and insert coalesce to form a continuous ring (18) of liquid which is held in
that condition and subsequently cured to form the top flexible diaphragm (14). |
[0001] This invention" relates to sealing arrangements being typically dust sealing arrangements wherein a pipe, nozzle, tube or the like must be sealed externally and peripherally.
[0002] A typical application of the invention relates to vacuum cleaner bags, being the replacement bags used in vacuum cleaners, the purpose of which is to collect dust and other particles picked up by the vacuum cleaner. The bag functions in that an inlet conduit or duct leads to the interior of the bag, and suction is. applied through the bag wall, which acts as a filter, and through the inlet tube. At one end of the inlet tube is a nozzle brush or the like, which is manipulable by the user for the picking up of dust, fluff and other particles, all of which is well known.
[0004] In the known construction, the top of the dust bag is closed by means of a plate member, which may be of stiff cardboard, and the member is provided with an aperture. Across the aperture is an elastic diaphragm, of latex, rubber or the like. The diaphragm has an aperture which is in register with the aperture in the plate, but is of smaller size, and to achieve the seal connection between the inlet tube and the dust bag, the inlet tube end is simply forced through the aperture-in the diaphragm, and the expansion of the diaphragm aperture and its resiliency effects a seal against the inlet tube. This seal is necessary to prevent the escape of dust, fluff and other material collected by the vacuum cleaner bag.
[0005] There are of course many applications where such sealing requirements arise, and the present invention applies to all such applications. Another application example comprises the mounting of filters in motor vehicles.
[0006] Presently, the diaphragms are produced from a rubber latex or the like sheet by a punching operation, and the diaphragm may be produced in a multiplicity at one operation of the punching machine. These diaphragms produced from rubber latex sheets are provided with an aperture or slits radiating from the centre and the tube to be sealed thereby is simply pushed through the aperture or the aperture which is in effect created by the slits. The diaphragms are thin, stretchable and generally floppy and because of this they are difficult to handle by machinery. Consequently, any operation involving the handling of the known diaphragms has been done by hand.
[0007] Thus, in the presently known method of manufacturing dust bags of the type described above, two operators are provided with a supply of diaphragms and plate members, and a glue pad and a supply of glue. The first operator applies the glue by means of the pad to the plate and the second operator applies the diaphragm by hand to the plate: This is operator time consuming and represents a high expense. Nevertheless, this method although expensive, is less expensive than providing machinery for handling the diaphragms.
[0008] Indeed, some,manufacturers of vacuum cleaner bags, including some manufacturers who make the vacuum cleaning equipment, simply do not use flexible diaphragms and design the plate to have a hole which approximates to the size of the inlet tube. This is unsatisfactory, because there is always clearance between the tube and plate hole through which air is drawn, rendering the vacuum cleaner inefficient.
[0009] Furthermore, the flexible sheet diaphragms referred to above are epxensive, and cost almost as much as the plates to which they are attached. The labour cost involved in applying the diaphragms to the plates is substantial, and as a result, the plate and diaphragm is an expensive item of the whole dust bag. When one considers that millions of dust bags are used annually, any small cost saving per bag will represent a large saving in total.
[0010] The present invention is concerned with the provision of a sealing diaphragm on the plate or other carrier member, whereby the process can be at least semi- automated, and will be much simpler, and much less expensive than the process of manufacturing the conventional bag.
[0011] According to the invention, in one aspect there is provided a sealing member, such as a vacuum cleaner dust bag closure plate with an aperture therein, and partially covering the aperture is a diaphragm of rubber latex or the like, said rubber latex or the like having been applied in fluent form by a coating, spraying, brushing, moulding or casting operation or the like directly to the plate member.
[0012] Preferably, the rubber latex or the like is applied in liquid form as a coating extending over the edge of the aperture, and the liquid latex or the like which overlaps the aperture is supported by a metal insert. The coating may be applied by spraying a jet of the material radially towards the centre of the aperture and by rotating the spraying device through 360° thereby to form a ring of the coating which overlaps the metal insert and overlaps the sealing member to which the coating becomes bonded when it has cured. The metal insert can be removed to leave a diaphragm of the rubber latex or the like material extending across the aperture.
[0013] In another and highly effective method of the invention, the latex or the like is dripped from a drip head which is rotated through 3600 as drips of latex fall therefrom. As the drips land they coalesce to form an even ring latex of which overlaps the edge of the insert and the edge of the plate. This has the particular advantage that the latex flows outwardly of where it drops and therefore tapers in thickness to a minimum at the ring edges.
[0014] Preferably, the head has two side by side outlets from which drips issue simultaneously, and subsequently coalesce when they land, with adjacent drips to provide a continuous ring of latex.
[0015] In each of the above arrangements, the latex is subsequently cured by heating to form a flexible but tough diaphragm or sealing ring overlapping the plate aperture, for flexible sealing to an inlet tube pushed through said aperture.
[0016] Alternatively, the diaphragm may be cast using a matching mould pair permitting the injection of the rubber latex or like material into a cavity defining the diaphragm, the mould pair being for co-operation through the aperture in the plate member.
[0017] The mould pair may comprise a plug and cap arrangement providing for the provision of a diaphragm of even thickness on one side of the plate member.
[0018] The invention in another aspect provides a method of applying a diaphragm to a carrier member such as a plate member of a vacuum cleaner dust bag, wherein the flexible diaphragm is formed by casting or moulding fluent material directly on to the plate member.
[0019] The invention also provides a machine for producing sealing members as aforesaid, wherein there is a means for holding the sealing member, and an applicator head for applying fluent latex or the like as a ring around the edge of the aperture in the sealing member so that the latex or the like flows over said edge, and means defining a supporting surface at the edge of the aperture to support the fluent latex or the like which flows over said edge and means for curing the latex until the sealing member and cured latex or the like forming a sealing ring overlapping the aperture, can be removed from the machine.
[0020] The applicator head preferably has at least one outlet and from which the latex or the like, in liquid form issues, and preferably a means is provided to cause the liquid to issue as drips, so that the drips will fall onto the sealing member whilst the head is rotated through 360° so that a ring of the liquid is formed, which is subsequently cured to form a flexible diaphragm. The head may have a pair of side by side outlets and is adapted so that drips issue therefrom simultaneously to form a ring of latex or the like of the required width.
[0021] The machine will have control means for controlling the flow of the latex or the like to ensure that flow takes place only when required and in sequence with the operation of the machine.
[0022] Thus, the machine may have a plurality of heads co-operating with a plurality of holders for making a plurality of sealing members simultaneously, and the holders may be on carriers which are adapted to pass into a curing oven after application of the latex or the like to sealing members placed on the holders. There may be a plurality of carriers carried by feed chains which travel into and out of the oven, and each, in turn, dwells at an application station whereat said heads are located. The heads are operated only when a carrier with sealing members on the holders is at said application station.
[0023] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:-
Fig. 1 is an exploded perspective view illustrating the conventional method of connecting a vacuum cleaner dust bag, its plate member and the diaphragm seal;
Fig. 2 shows the dust bag of Fig. 1 in assembled condition;
Fig. 3 is a perspective view of a machine for manufacturing sealing members according to the present invention;
Fig. 4 is a perspective view of one of the heads of the machine illustrated in Fig. 3, when in operation;
Fig. 5 is a sectional elevation of the sealing member and the holder shown in Fig. 4, the section being taken on the line V - V of Fig. 4;
Fig. 6 is a perspective view of the sealing member after completion of manufacture thereof;
Fig. 7 is a sectional elevation of the sealing member of Fig. 6, the section being taken in the line VII - VII of Fig. 6
Fig. 8 shows in exploded perspective view of how the diaphragm of a dust bag may be produced according to another embodiment of the present invention;
Fig. 9 shows a sectional elevation of the mould assembly of Fig. 8 with the plate member positioned in relation thereto;
Fig. 10 shows the plate member shown in Fig. 8 with the diaphragm applied;
Fig. 11 is a perspective view showing how the diaphragm is formed according to a further embodiment of the invention;
Fig. 12 shows the arrangement of Fig. 11 in sectional elevation; and
Fig. 13 shows in elevation similar to Fig. 10 a plate member of a dust bag with the diaphragm applied according to the embodiment of Fig. ll.
[0024] Referring to the drawings, and firstly to Fig. 1, a vacuum cleaner dust bag comprises three components namely a filter bag 10 which is closed at the bottom (not shown) end, a closure plate member 12 which also forms the means for location of the dust bag in the vacuum cleaner, and a flexible sealing diaphragm 14 which is in the form of a thin sheet of rubber latex. The plate member 12 has an aperture 16 for receiving the end of the vacuum cleaner inlet tube, and the diaphragm 14 has an aperture 18 of smaller size than aperture 16, and through which the end of the inlet tube is forced to provide a seal as will be explained. The sheet 14 is stuck to the underside of plate member 12 in the area 20, so that aperture 18 is concentric with aperture 16, and the top of the bag 10 is adhered to the underside of the plate 12 along the line 22, so that the open top surrounds the diaphragm 14. It should be mentioned that in some other embodiments, the diaphragm 14 is laminated between two plate elements each shaped as plate member 12 to provide a laminated plate member. The plate member 12 may be of cardboard. .
[0025] Fig. 2 shows the completed dust bag, and it will be seen that the filter bag 10 is in fact flattened and the bottom end is sealed by folding same on itself and adhering the fold portions one to another.
[0026] To utilise the bag as shown in Fig. 2, it is inserted in the appropriate position in the vacuum cleaner, the plate member 12 forming the location and support means for the bag, and the inlet tube is simply pushed through aperture 18 and the'diaphragm, which expands and by its resilience forms a seal around the tube end.
[0027] The known arrangement suffers from the disadvantages indicated herein, that the manufacture of the bag is labour intensive, involving the cutting of the diaphragm 14 from sheet stock material, and the application of same to the plate member 12.
[0028] In Fig. 3 is shown in schematic elevation a machine for the manufacture of the dust bag plate or sealing members according to the invention. Only the relevant parts of the machine are indicated, and immaterial mechanical and electrical details have been omitted in the interests of simplicity. The machine is indicated generally by reference 30 and comprises a casing 32 defining an oven through which parallel chains 34 pass. The chains being guided by guide sprockets 36 and being driven by a guide motor 38. The chamber 32 is in fact an oven for curing the composition which is applied to the plate members as will be explained. Between the chains extend carrier bars 38, and as shown to the front side of the machine, each carrier bar carries in this case four holders 40 for receiving the plates to be treated. The chains 34 pass out of the front of the machine and over support sprockets 42 before passing back into the machine oven chamber. Therefore, an operator standing in front of the machine can load the holders 40 with plates to be treated. To the front of the machine are four application heads 44 for applying composition to the plates carried by the holders 40, as will be explained hereinafter, the composition being supplied from a tank 46 through a conduit 48, a control pump 50 and flexible supply lines 52 which lead to the discharging portion of the respective heads 44. Detecting devices 54 are arranged in appropriate position in relation to one of the chains 34 so as to detect when a carrier 38 is in appropriate position under the heads 44 to receive the composition as will be explained. When the sensing devices 54 sense that a carrier is'in the correct position, the motor 38 is stopped by sending a signal over control line 56, the pump 50 is caused to supply composition to the heads 44 via a control signal over line 58, and finally a further control signal is sent over line 60 to a displacement device 62 in the form of a piston which displaces a horizontal rack 64 which co-operates with each of the heads 44 in a manner to rotate the dispensing portion for the effective distribution of the composition as will be explained hereinafter.
[0029] The general operation of the machine shown in Fig. 3 is that an operator stands in front of the machine and places plates in position on the holders 40 whilst the plates carried by the said holders under the heads are being treated. When the treatment has been completed, the treated plates held by the holders are moved into the oven chamber 32 and the next carrier on which the plates to be heated have been placed moves under the heads to have composition applied thereto and so the process continues. The chains 34 are fed at such a speed so that by the time each carrier has moved into and through the oven chamber 32 which is thermostatically controlled, the composition which is supplied by the heads has cured to provide elastic diaphragms on the plates. The operator also removes the completed plates prior to placing fresh plates to be treated on the holders 40.
[0030] The specific application of the composition to the plates will now be described with reference to Fig. 4 which shows a single plate carried by a holder and also shows the relevant portions of the applicator head. In Fig. 4 the carrier bar 38 is shown, and the holder 40 carried thereby. The holder 40 as best shown in Fig. 5 is provided with an upstanding insert disc 64 which is matched to the inner diameter 68 of the dust bag plate shown in Fig. 4 by reference 70. This plate 70 is of cardboard or the like material. The plate 70 is generally rectangular with cut-outs 72, and the holder 40 is a plate of similar dimension. The height of the insert 64 is substantially equal to the thickness of the plate 70 as shown in Fig. 5, so that the top surface of the insert 64 lies flush with the top surface of the plate 70. When the holder 40 is in the location for receiving the composition, it registers precisely with a rotatable wheel 76 of the applicator head, such wheel 76 having on its periphery a ring of gear teeth 78 which meshes with the said rack 64 illustrated in Fig. 1. When the rack is reciprocated as indicated by the arrow 66 in Fig. 4, the wheel 76 turns through 360°.' In this connection, it is to be pointed out that the feed tubes 52 shown in Fig. 4 pass through the wheel 76 and have outlet nozzles 78 from which the composition in liquid form drops as illustrated by two rows of drops 80. The two rows of drops are provided because in fact there are two tubes 52, and the use of two rows of drops in this embodiment provides for a band of composition of the correct width, as will be explained. The nozzles 78 are offset from the centre of the wheels 76, which is also the centre of the aperture 68 so that as shown in Fig. 4 when the composition drops onto the plate 70 and the insert 65, a ring 80 of the composition forms which overlaps the top of the plate 70 and the surface of the insert 65. It should be mentioned that although the composition is in liquid form, its consistency is such that when the drops land as shown in Fig. 4, the drops coalesce and a ring as shown in 50 is formed. The surface tension of the composition ensures that the ring remains continuous. This can easily be achieved by trial and error. The drip of composition is controlled so as to terminate after a revolution of 3600 of the wheel 76 so that there is no composition excess resting on the plate and insert 65.
[0031] As shown in Fig. 5 by virtue of the surface tension of the composition it takes up a humped cross-section tapering to substantially zero thickness at the inner and outer edges 80A and 80B, and when the holder the plate and composition pass through the oven chamber the composition cures to form a flexible diaphragm of substantially the same shape as illustrated in Fig. 7, the cured composition bonds to the plate but not to the insert. Fig. 6 also shows the plate with the composition applied, but in perspective elevation.
[0032] Any suitable composition to provide a flexible diaphragm may be provided, but a preferred material is a latex composition sold by
under the name , and the applicator heads preferably are set to rotate at a speed of revolutions per minute with a composition drip rate of cc per revolution.
[0033] The cure time for composition applied to such quanity is in an oven chamber maintained at a temperature of .
[0034] If reference is made to Fig. 7, the cured composition 80 now forms a flexible diaphragm in that the portion 84 which overlies the aperture 68 in the plate 70 can form a seal with the inlet tube of the vacuum cleaner as it is pushed through the aperture 86 formed by the diaphragm 80 in much the same way as it is pushed through the aperture 18 in the flexible diaphragm 14 in the known arrangement.
[0035] The resulting plate members with the flexible diaphragm are attached to the dust bags by conventional means.
[0036] Plate members and dust bags produced by the method and machinery described with reference to Figs. 3 to 7 can be produced much more cheaply than conventional dust bags, because it is not necessary to purchase and handle flexible sheet diaphragms, nor is it necessary to apply the diaphragms, and a single operator can produce a plurality of the plates with flexible diaphragms according to the invention simultaneously. The present invention can take other forms and several alternative arrangements will now be described. Referring to Fig. 8, plate member 100 is again illustrated, but also illustrated are two moulding components 102 and 104, the component 102 being a male plug made up of a number of sections of circular form but of different diameter. A rear plate section 106 is for positioning flush with the rear face and the plate member 100, an intermediate section 108 is of the same thickness as the plate member 100 and fits neatly in the plate member aperture 110, and a top section 112 is for co-operating with a central recess 114 of the female member 104. The female member 104 has a flange 116 with a recess 118 of circular form and of the depth equal to the thickness of the diaphragm which is required of the plate member.
[0037] If reference is made to Fig. 9, the manner of functioning of the mould can be readily understood, because the mould parts are shown in assembled relationship with the plate member 100. It is seen that the recess,118 forms a cavity 120 to which the composition, again suitably rubber latex, can be injected through passages 122 in the member 104, and 124 and 126 in the, member 102. Passage 124 is an axial passage located centrally of member 102, and leads to radial distribution passages 126 to ensure that when the latex is injected through passages 122 and 124, it is evenly distributed throughout the cavity 120. It will be noticed that the cavity 120 is defined partly by the top surface of the plate member 100, and partly by the top surface of intermediate section 108 of the male member 102. This results, as shown in Fig. 10, in the formation of a diaphragm 128 which overlaps the plate aperture 110, and defines a sealing aperture 130 for receiving the end of the inlet tube in much the same manner as aperture 18, except that aperture 130 is larger than aperture 18, because it has been found in practise that the aperture 18 need not be as small as is in fact used. During the moulding of the diaphragm 128, the material of same as in the Figs. 3 to 7 embodiment bonds firmly to the top surface of plate 100, whereby the use of a separate adhesive is not necessary.
[0038] The latex will usually be required to be heated in order to effect curing of the latex, and in a preferred arrangement, the moulds may be carried by conveyors, and the process can be automated, so that plate members 100 with diaphragms 128 applied thereto can be discharged on a continuous basis from a conveyor, in much the same manner as in Fig. 3.
[0039] Referring now to Figs. 11 to 13, a plate member 100X has an aperture 102X in which is neatly fitted a metal washer 104X having a central bore 106. A spraying device 108 has a nozzle 110 for the spraying of rubber latex or the like material which is supplied to the nozzle 110 by means not shown, but which may be similar to that shown in Fig. 4. Spraying device 108X is mounted so that the rubber latex or the like material 112X issuing from the nozzle impinges upon the plate member 100X adjacent the aperture 102X, but flows inwardly over the upper surface of the metal washer 104X which is flush with the upper surface of the plate member. The surface tension effects on the rubber latex or the like material as related to contact with the metal of the washer 104X ensures that the coating flows freely on the washer, and as the spraying device 108X is rotated as indicated by the arrow 114X, so an annulus of the coating as shown in Fig. 13 is formed which overlaps an edge region of the plate member 100X and becomes adhered thereto and also overlaps the washer 104X, as shown in Fig. 12. When the annular coating 116X has been cured, (for example as described previously), the washer 104X is removed leaving the arrangement as shown in Fig. 13 in which the coating extends across the edge 102X defining the plate aperture thereby to provide a diaphragm which is substantially as shown in Fig. 7 and which acts as a seal upon a tube or conduit of larger diameter than aperture 106X and inserted into the aperture 106X of the diaphragm.
[0040] The process of the embodiment of Figs. 11 to 13 as the Figs. 3 and 4 process can be automated in order to achieve higher production rates. For example there may be a plurality of jigs providing washers 104X in a line, to which are fitted the plate members 100X. These jigs and plate members are presented to the spray heads 108X which operate simultaneously and apply the annular diaphragm coatings 116X, and the jigs and coated plate members 100X may then be passed direct to a curing oven, and only when the diaphragms 116X are sufficiently cured and adhered sufficiently to the card 100X are they removed from the jigs 104X which may be circulated by means of endless chains back to the spraying heads.
1. A sealing member, such as a vacuum cleaner dust bag closure plate with an aperture
therein, partially covering the aperture is a diaphragm of rubber latex or the like,
said rubber latex or the like having been applied in fluent form by a coating, spraying,
brushing, moulding or casting operation or the like directed to the plate member.
2. A sealing member according to Claim 1, wherein the rubber latex or the like is
applied in liquid form is a coating extending over the edge of the aperture, and the
liquid latex or the like which overlaps the aperture is supported by an insert.
3. A sealing member according to Claim 2, wherein the coating is applied by spraying
a jet of the liquid readily towards the centre of the aperture and by rotating the
spraying device through 3600 thereby to form a ring of the coating which overlaps the insert and overlaps the
sealing member to which the coating becomes bonded when it has cured.
4. A sealing member according to Claim 2, wherein coating material is dripped from
a drip head which is rotated through 360° over a dust bag or a vacuum cleaner comprising
a filter bag portion attached to a sealing member according to any of the preceding
Claims.
5. A method of producing a sealing member, such as a plate member or vacuum cleaner
dust bag, wherein fluent material such as rubber latex or the like which cures to
flexible form is applied by a coating, spraying, brushing, moulding or casting operation
or the like directly to a plate member with an aperture therein so as to overlap the
edge of the aperture, and the fluent material forms a ring which is cured and anchors
to the plate member but overlaps the aperture to provide a flexible sealing diaphragm
to seal against a tube or head pushed through the aperture.
6. A method according to Claim 5, wherein the rubber latex or the like is applied
in liquid form as a coating extending over the edge of the aperture, the liquid latex
or the like which overlaps the aperture being supported by a metal insert until the
composition cures.
7. A method according to Claim 6 when the coating is applied by spraying a jet of
the composition radially towards the centre of the aperture and by rotating the spraying
device through 360° to for the ring of the coating.
8. A method according to Claim 6, wherein the latex or the like material is dripped
from a drip head which is rotated through 3600 as drips of latex fall therefrom, to form a ring of latex which is subsequently cured,
the rate of the drip and the number of drips being such that the drips when they land
coalesce to form an even ring of composition which overlaps the edge of the insert
and the edge of the plate, followed by curing the latex material.
9. A method according to Claim 7, wherein the head has two side by side outlets from
which drips issue simultaneously and subsequently coalesce when they land.
10. A machine for producing sealing members as referred to herein, wherein there is
a means for holding the sealing member, and an applicator head for applying fluent
latex or the like as a ring around the edge of the aperture and the sealing member
so that the latex or the like flows over said edge, and means defining a supporting
surface at the edge of the aperture to support the fluent latex or the like flows
over said edge, and means for curing the latex until the sealing member and cured
latex or the like forming a sealing edge overlapping the aperture can be removed from
the machine.
11. A machine according to Claim 10, wherein the applicator head has at least one
outlet out of which the latex or the like in liquid form issues.
12. A method according to Claim 11, wherein a means is provided to cause the liquid
to issue as drips from the said outlet so that the drips will fall onto the sealing
member whilst the head is rotated through 360° so that a ring of the liquid is formed,
which is subsequently cured to form a flexible diaphragm.
13. A machine according to Claim 12 wherein the head has a pair of side by side outlets
located on different radii and is adapted so that the drips issue therefrom simultaneously
to form a ring of latex or the like of the required width.
14. A machine according to any of Claims 10 to 13, wherein the machine has a plurality
of heads co-operating with a plurality of holders for making a plurality of sealing
members simultaneously, and the holders are on carriers which are adapted to pass
into a curing oven after application of the latex or the like to sealing members placed
on the holders.
15. A machine according to Claim 14, wherein there is a plurality of carriers, carried
by the feed chains which feed chains travel into and out of the oven, and each, in
turn, dwells at an application station whereat said heads are located.