GB2330524A

GB2330524A - Process for making a domestic work top

Info

Publication number: GB2330524A
Application number: GB9821876A
Authority: GB
Inventors: Luciano Lorenzetti; Giannino Sandrin
Original assignee: Ro SA S A S; Electrolux Zanussi Elettrodomestici SpA; Electrolux Zanussi SpA
Current assignee: Ro SA S A S; Electrolux Zanussi Elettrodomestici SpA; Electrolux Zanussi SpA
Priority date: 1997-10-23
Filing date: 1998-10-07
Publication date: 1999-04-28
Anticipated expiration: 2018-10-07
Also published as: ITPN970056A1; GB2330524B; GB9821876D0; DE29818664U1; ES2173008B2; IT1296333B1; ES2173008A1

Abstract

A worktop for a domestic appliance (eg a washing machine) is made by injection moulding a plastics frame (1, Fig 1) having a turned-in edge 4 and a facing flange 6 between which is inserted a chipboard panel 10. The flange 6 is wider than the edge 4 and has a series of holes 9 along its attachment edge 7 with the frame. A sealing material eg silicone-based is injected through the holes to fill the space between the edges 13 of the panel and the inside surfaces 5 the frame walls 2.

Description

1 2330524 PROCESS FOR THE PRODUCTION OF A WORKTOP FOR DOMESTIC APPLIANCES

AND THE LIKE AND THE WORKTOP PRODUCED IN THAT WAY The present invention relates to a process for the production of a worktop for domestic appliances and the like and to the worktop produced in that way.

It is known that worktops (also known as a cover top or simply as a top) are used on domestic appliances such as front-loading clothes washing machines, dishwashers and refrigerators which are of free-standing type or of the type to be positioned beside units in order to produce the upper part of the casings thereof, more especially when their maximum height from the ground, in accordance with the European standards, does not exceed 90 centimetres.

is A worktop of that kind performs both functional and aesthetic purposes and is generally not made in one piece but consists of a flat panel, generally produced with chipboard wood which is veneered on the face which is in view, and an associated frame generally of injection-moulded plastics material. Those two parts are produced separately and then joined together.

A first known worktop structure provides for making the frame in the form of two C-shaped elements which can be coupled together in slidably inserted relationship in such a way as to hold the panel along the lower edge thereof by means of clinching engagement, see GB-A-2 165 747. The disadvantage of that structure is the absence of any sealing effect whereby there is nothing to prevent the infiltration of liquid under the worktop. Safety problems can then arise in the case of voltage-carrying electrical components which may be fitted without adequate protection on a control panel of the apparatus which is disposed beneath the worktop. If, to obviate that disadvantage, resins of the 'hot melt' type are used for the glueing operation, a fairly rigid joint is produced which, besides the risk of giving rise to undesirable warping or buckling of the panel, makes it almost impossible to recycle the worktop at the end of the useful life of the appliance on which it was fitted.

2 Another known design provides for using two 'concentric' quadrilateral frames. The first (internal) frame which is made from a low-grade material and provided with hooks or clips and supports since it is to perform a structural function serves to hold a panel of chipboard wood. That frame is then enclosed by the application of force in a second (external) frame having a pronounced aesthetic function and thus being particularly well refined. Examples of that design are set forth in European patent application No. 672 368 and in published Italian patent application No.

MI 93A000061.

An obvious negative aspect of that second design lies in the substantial outlay of materials for provision of a double frame over the entire perimeter of the panel. Furthermore, in the first prior art mentioned, provision is made for the insertion of a resilient sealing member between the periphery of the panel and the internal frame, indeed in an undercut configuration, which makes the procedure fairly difficult. In turn the second art provides for fixedly mounting the external frame, preferably when it has not yet completed the thermal contraction phase, on the internal frame with the very real risk of damaging the external frame, for example with scratches or dents.

In the field of domestic appliances and more precisely in the production of 'smooth-surface' cooking tops and hobs, it is also known to use glues for joining together two parts - that is to say a -metal frame and a glass ceramic plate - which are not deformable, for example under the effect of weight supported by the glass-ceramic plate or overflowing liquid from the pans. The glue along the periphery of the glass-ceramic plate must remain rigid in respect of time in such a way as to prevent the infiltration of liquids into the subjacent space which accommodates the heating elements see for example EP-A-0 162 621. Conversely, in the case of the present invention, the parts to be joined - that is to say the frame of plastics material and the chipboard panel which is only of a thickness of the order of around 10 millimetres - are anything other than rigid and therefore the glueing thereof must remain elastic 3 so as to prevent any deformation during usage. All that being said, the applicants do not consider that that procedure constitutes a pertinent state of the art in relation to the present invention.

An aim of the present invention is to provide a process for the production of a worktop of the type and for the use mentioned hereinbefore which is rational and can be produced industrially in a simple manner and at moderate cost in such a way that it can also be used for very high production volumes. Another aim of the invention is to prevent any deformation in use, in particular in respect of the flat panel of chipboard wood, for example caused by weights placed on the surface thereof which is in view and liquids inadvertently poured on to same.

According to the present invention there is provided a process for the production of a worktop for domestic appliances and the like which comprises: a phase (A) in which a relatively flexible frame is injection moulded, the frame being produced with plastic material and having a peripheral rim portion having a first rectilinear edge and a second edge which is bent towards its interior; a phase (C) in which a flat panel is inserted into the frame in such a way that one face thereof is retained by said bent edge; a phase (E) in which a fluid sealing material is injected into the interior of the frame in order to effect peripheral sealing of the worktop, wherein, in the injection-moulding phase a flange is also produced, starting from the peripherally inward surface of said rim portion, the flange extending substantially parallel to said bent edge and being of a width which is greater than the width of the bent edge, after or at the same time as the moulding phase there is provided a phase (B) in which a discrete number of through holes are produced along the attachment edge of said flange in such a way that the axis thereof is parallel to said peripheral rim portion, and is 4 cz by means of the phase of insertion of the panel it is provided that the other face of the panel is held by said flange and that the peripheral edges remain spaced from the peripherally inward surface of said rim portion thereby to permit the use of a preponderant part of said through holes for said sealing material injection phase.

The invention also provides a worktop for domestic appliances and the like which comprises a relatively flexible frame produced with plastics material with a peripheral rim portion having a first rectilinear edge and a second edge which is bent towards its interior and a flat and relatively rigid panel which is preferably made with chipboard wood and which is inserted into the frame in such a way that a face thereof is held by said bent edge, characterised by being produced according to.at least one of the preceding claims.

The subject and the advantages of the present invention will be clearly apparent from the following description of an embodiment with reference to the accompanying drawings in which:

Figure 1 shows a block diagram of the essential phases of the process of the invention; Figure 2 is a perspective view showing, separately from each other, the plastics frame and the chipboard panel which are the essential components of a worktop of the type and for the use mentioned hereinbefore; and Figure 3 shows a view in transverse (vertical) section of a peripheral zone of a finished worktop.

Referring to the block diagram in Figure 1, the first phase A in the process of the invention comprises the injection-moulding in one piece of a quadrilateral frame 1 made from plastics material. For the sake of simplicity, the description and representation of details will be omitted (reinforcing ribs, brackets for fixing the worktop to the casing of a domestic appliance or the like) which, although moulded in one piece with the frame, are not directly pertinent to the subject of the invention.

As shown in Figure 3 the section of the frame 1 comprises a peripheral rim portion 2 which terminates respectively with a first rectilinear edge 3 which is rounded off at the end and with a second edge 4 which is bent substantially at a right angle, and in practice is horizontal. At a certain distance c from the second edge 4 (which distance is equal to or slightly greater than the thickness of the panel 10 of veneered chipboard wood) extending from the peripherally inward surface 5 of the rim portion 2 is a tongue or flange 6 of a width as indicated at a, which is substantially parallel to the bent edge 4, of a width b that is less than a, of the rim portion 2. The edge 7 of attachment of the flange 6 to the surface 5 of the rim portion 2 is preferably but not exclusively disposed slightly higher than the rest of the flange or tongue so as to constitute a step 8.

In accordance with a feature of the invention the is process provides a step B for drilling the flange 6 along the attachment edge 7 in order to produce a discrete number of circular holes 9, the axis Z of which is parallel to the rim portion 2, that is to say vertical. Even if, speaking in conceptual terms, the drilling step B is an operative phase that is separate from the operation of injection- moulding the frame 1, in practice in can also be effected at the same time as the moulding operation by virtue of the fact that the first edge 3 of the rim portion 2 is rectilinear and rounded off whereby it leaves free access (from below) to that attachment edge 7 for the tools, punches or stamps rather than drill bits, which are used to produce the holes 9.

In all the modes of manufacture the choice of material with which it is produced and the dimensional relationships should give rise to a frame 1 which is relatively flexible with respect to the panel 10 even if (as already stated above) the latter is anything other than rigid. By way of indication, in a rectangular frame 1 of ABS, made in one piece and measuring 60 x 60 centimetres, with a peripheral rim portion 2 of a height h of 30 millimetres, the width of the tongue or flange 6 can be a=17 millimetres, that of the edge 4 can be b=10 millimetres and the tongue or flange 6 can extend to a distance c=10 millimetres from said edge 4 if the panel 10 is of thickness of 10 millimetres. It is also possible to provide n=20 holes 6 of a diameter d=3.5 millimetres which are equidistantly distributed all along the perimeter and 4 holes at the corners of the frame 1.

The process of the invention then provides an operation C in which a rectangular panel 10 made of faced or veneered chipboard wood is inserted into the frame 1 by making use of the inherent elasticity thereof, in such a way that its faces 11 and 12, over all the four edges are respectively held by the tongue or flange 6 and the bent edge 4 of the rim portion 2. As shown in Figure 3 the dimensions of the panel 10 and the frame 1 must be selected in such a way that the four peripheral edges 13 of the panel 10 remain in the interior of the space occupied by the holes 9 so as to bear against the optional step 8 possibly formed by the is attachment edge 7 of the tongue or flange 6.

At that point, in particular in the event that the above-mentioned step 8 is absent, the process of the invention can provide an operation D for clamping or clinching the panel 10 to the tongue or flange 6 in such a way that the edges 13 thereof leave free the attachment edge 7 of the tongue or flange 6 and thus spaced from the peripheral rim portion 2 of the frame 1.

The subsequent phase E in the process of the invention comprises an injection of a sealing material through almost all of the holes 9 (some holes serve in fact for the discharge of air during the injection operation). In that way the sealing -material completely fills the space which there is, over all four edges, between the lateral edges 13 of the panel 10 and the inside surface 5 of the rim portion 2 of the frame 1, producing perfect peripheral sealing integrity. The preselected sealing material must maintain the appropriate elastic characteristics with the passage of time in order to avoid any deformation of the panel 10 and/or the frame 1 during operation. Single- component thixotropic or silicone sealing materials have proven themselves to be particularly suitable.

Preferably the injection of sealing material which is effected under low pressure (for example at 4 - 6 kg/ CM2 in the case of single-component thixotropic sealing material) 7 takes place simultaneously in all the holes. According to convenience it is possible to use either a plurality of distributors or a plurality of injection heads which are fed from a single sealing material container. 5 The main advantage afforded by the invention is that the glued joint maintains the appropriate elasticity in the course of time, thus avoiding undesirable warping or buckling of the panel 10 and/or the frame 1. A second advantage lies in the fact of being able to use a single frame both for structural and for aesthetic functions.

A further advantage is that, for implementation of the phase E, there is no requirement for particular moulds which would constrain the frame 1 (with the danger of damaging the surface thereof) or masking arrangements which would protect it from any dribblings of sealing material and not even any final polishing. It is in fact noted that it is the actual configuration of the frame 1, in particular of the bent edge 4 and the flange 6 with the injections holes 9, to prevent any discharge of the sealing material 15 from the peripheral space defined by the four lateral edges 13 of the panel 10, the inside surface 5 of the rim portion 2, the bent edge 4 and the tongue or flange 6 of the frame 1.

A further advantage lies in the possibility of separating the frame 1 from the panel 10, in the case in question at the end of the useful life of the appliance to which the worktop is fitted to recover and recycle the respective materials.

8

Claims

CLAIMS is 1. A process for the production of a worktop for domestic

appliances and the like which comprises: a phase (A) in which a relatively flexible frame is injection moulded, the frame being produced with plastic material and having a peripheral rim portion having a first rectilinear edge and a second edge which is bent towards its interior; a phase (C) in which a flat panel is inserted into the frame in such a way that one face thereof is retained by said bent edge; a phase (E) in which a fluid sealing material is injected into the interior of the frame in order to effect peripheral sealing of the worktop, wherein, in the injectionmoulding phase a flange is also produced, starting from the peripherally inward surface of said rim portion, the flange extending substantially parallel to said bent edge and being of a width which is greater than the width of the bent edge, after or at the same time as the moulding phase there is provided a phase (B) in which a discrete number of through holes are produced along the attachment edge of said flange in such a way that the axis thereof is parallel to said peripheral rim portion, and by means of the phase of insertion of the panel it is provided that the other face of the panel is held by said flange and that the peripheral edges remain spaced from the peripherally inward surface of said rim portion thereby to permit the use of a preponderant part of said through holes for said sealing material injection phase.

2. A process for the production of a worktop for domestic appliances or the like according to claim 1, wherein said phase of insertion of the panel is effected by making use of the relative elasticity of said frame with respect to the panel.

9 3. A process for the production of a worktop for domestic appliances or the like according to claim 1 or claim 2, wherein said sealing material injection phase takes place simultaneously in all said through holes which are used for 5 the injection operation.

4. A process for the production of a worktop for domestic appliances and the like according to any one of claims 1 to 3, wherein a singlecomponent thixotropic sealing material is used during said injection phase.

5. A process for the production of a worktop for domestic appliances and the like according to any one of claims 1 to 3, wherein a singlecomponent silicone sealing material is used during the injection phase.

6. A process according to any one of the preceding claims wherein said flat panel is made with chipboard wood.

7. A worktop for domestic appliances and the like which comprises a relatively flexible frame produced with plastics material with a peripheral rim portion having a first rectilinear edge and a second edge which is bent towards its interior and a flat and relatively rigid panel which is preferably made with chipboard wood and which is inserted into the frame in such a way that a face thereof is held by said bent edge, characterised by being produced according to at least one of the preceding claims.

8. A process substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A worktop for domestic appliances substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.