DEVICE AND METHOD FOR AT LEAST PARTIALLY ENCAPSULATING A SUBSTANTIALLY SHEET SHAPED ELEMENT

Abstract: The invention relates to a device for at least partially encapsulating a border of a substantially sheet shaped element, said device comprises a mould having at least two parts (2, 3) for pressing there between said element (1), said mould being provided with means for forming, when said element is pressed between parts of said mould, a cavity around said border, said device further comprising injection means for injecting a moulding substance into said cavity. Said means for forming said cavity comprise an elastically deformable member (4) having a profile and which extends along an encapsulation borderline of said element and which is provided to be elastically deformed while maintaining a tight contact along said encapsulation borderline when a pressure is applied thereon in order to follow irregularities in said element along said borderline. The invention also relates to a method for at least partially encapsulating a border of a substantially sheet shaped element.

Description: The present invention relates to a device for at least partially encapsulating a border of a substantially sheet shaped element, which device comprises a mould having at least a first part and a second part for pressing said element therebetween and for defining a cavity around said border, said first part comprising an elastically deformable contact member which is slidably mounted in the first part and urging means for urging said contact member at least against said element, which device further comprises injection means for injecting a moulding substance into said cavity. Such a device is disclosed in EP-A1-0 127 546 and is used for encapsulating the border of for example windows for automobiles. The manufactured sheet of glass is placed between the parts of a mould in order to encapsulate at least a part of the border of the window. Generally flexible plastic gaskets or seals are used for that purpose. However, EP-A1-0 127 546 discloses also the use of metallic seals having a flat contact surface destined to be pressed against the sheet shaped element. The metallic seal is, more in particular, slidably mounted in one mould part and pressed by springs with its whole flat contact surface against the sheet shaped element. When the mould is closed and the sheet shaped element is pressed between the parts of the mould, there is formed a hollow cavity around the part of the border to be encapsulated. In said cavity a moulding substance is injected in order to form a ring of elastomer around the glass, which serves to make a junction, having preferably an aerodynamical profile, between the car body and the sheet of glass. A drawback of the known device is that, due to the fact that the used sheet shaped elements always show irregularities at their surface, e.g. thickness variation and changes of bending radius, the encapsulation can not be realised correctly. As more and more automobile windows have bent surfaces in two directions, the encapsulation technique becomes more and more complex. Usually, use is made of elastomer gaskets or seals, such as rubber blocks, which are embodied in the mould surfaces in order to form at least a part of the cavity. These gaskets also serve to prevent the flow of the moulding substance out of said cavity. These elastomer gaskets have the disadvantage of imperfect parting lines, since they tend to camber when to much pressure is applied thereon. Further they also need regular cleaning and maintenance, and their life time is limited. Due to these deficiences of the elastomer gaskets, leakages of the moulding substance are creating flashformation at the surroudings of the element to be encapsulated. These flashes need then to be removed, which implies additional costs and causes damages on the element to be encapsulated. Also when use is made of metallic seals which are pressed by means of springs with their flat contact surfaces against the sheet shaped element, flashformation may occur due to irregularities onto the surface of the sheet shaped element. It is an object of the invention to realise an encapsulating device wherein said flashformation is substantially reduced. To this end, a device according to the invention is characterised in that said contact member is provided to be pressed by said urging means against said element and also against said second part so as to define together with this second part said cavity around said border and so as to be deformed in such a way that a tight contact is realized between said contact member and said element. By means of the pressure applied on said elastically deformable contact member, said contact member will be elastically deformed and will follow the variation of the glass thickness and bending radius. The profile will also be bend along the encapsulation borderline, thus causing a tightly packing between the contact member and the element to be encapsulated. Due to that tight packing flashformation is now prevented. In a preferred embodiment, a device according to the invention is characterised in that said member is formed by an elastically deformable metal ring, preferably a floating steel ring. Such a metal ring has excellent elastic properties, which makes him particularly suitable for deformation. Further a metal ring is a hard material having a considerable life time. In another preferred embodiment of a device according to the invention, at least one land face of said member is somewhat oblique with respect to the element on which it is applied, respectively to a part of the mould. Thus the edges beside the cavities formed by the element and the member touch first the element surface respectively the surface of the mould and provide a sharp ending of the encapsulation profile which thus prevents flashforming. A further embodiment a device according to the invention is characterised in that bellows are fixed on at least one of said parts of said mould for applying a pressure on said member, said bellows extending substantially along said member. By using bellows the force can be proportioned in function of surface variations of the element to be encapsulated. Preferably said member is provided with longitudinal and/or transversal grooves in a surface opposite to the one coming into contact with said element. Those grooves situated at the bellow side improve the flexibility of the member. The invention also relates to a method for at least partially encapsulating a border of a substantially sheet shaped element. The method according to the invention is characterised in that while pressing said contact member against the sheet shaped element, it is also pressed against said second mould part so as to define said mould cavity by means of said contact member and said second mould part whereby irregularities in said elements along said cavity are compensated for by elastic deformation of said member so that a tight contact is realized between said member and said element. Further details of the invention will now be given by way of an example in the drawing. In the drawings : Figure 1 shows a plane view of an elastically deformable metal ring according to the invention. Figure 2 shows a cross-section view (along the line II-II of figure 1) in its open state of a device according to the invention. Figure 3 shows the same device but now in its closed state. Figure 4 shows an analogous cross-section as the one illustrated in figure 2, but using an encapsulation member provided with longitudinal grooves. In the drawings, the same reference numbers relate to the same or analogous elements. The device shown in cross-section in figure 2 comprises an uppermould 2 and a undermould 3. A sheet shaped element 1, for example a sheet of glass or a sheet of plastic, is put on the undermould. The uppermould is provided with bellows 5 which, when blown up, apply a pressure on a member 4, which is located in a groove 8 of the mould. Preferably there is left a gap, for example of 0,2 mm thickness, between the member 4 and the uppermould 2. This is done for a frictionless movement of the member 4 in the groove 8 and for assuring that the bellows can not stick into the gap between the member and the uppermould. When the mould is open, as is shown in figure 2, the member 4 is kept in place by means of the bolts 7. The member 4 as shown in figure 1, is formed by an elastically deformable member made of a hard and wear resistant material, preferably a metal ring or a floating steel ring which at its underside shows a profile 6. Various profiles 6 are possible, each of them being each time adapted to form an encapsulation profile which fits into the profile of the frame into which the sheet shaped element has to be embedded. As is illustrated in figure 1 the outer circumference of the member 4 is adapted to fit with the other circumference of the element to be encapsulated. In the chosen example the ring 4 shows the shape of the window of an automobile. The member 4 is provided with projections 11 having a hole 14 through which the bolt 7 passes. Those projections serve to fix the member on the mould. The member 4 is also provided with an injection aperture 13 through which a moulding substance is injected. The injected moulding substance is applied to a buffer 12 from which it passes to a cavity 9 formed by the profile 6 of said member 4. Preferably the ring is provided with longitudinal grooves 10 in its upper surface, such as shown in figure 4. These grooves improve the flexibility of the metal ring. The grooves must be filled up afterward for example with plastic strips, to become again a smooth surface on which the bellows presses. The ring can also be provided with transversal grooves (not shown) in its upper surface, which can be applied either in combination or not with said longitudinal grooves. Along the encapsulation border, i.e. along the respective line perpendicular on the points B and D, and preferably also on the point C, the member 4 is provided with a sharp profile which extends along an encapsulation borderline of the element 1 and which is provided to form a tight contact between that member 4 and the sheet shaped element 1, when pressed thereon. The land faces of the ring are preferably a little bit oblique (0.5° to 1°), as can clearly be seen in figure 3 (lines EB, FD and CG) where the mould is closed. The member 4 and the undermould 3 are provided with oblique end faces 16 and 15, respectively. When the member 4 is moved towards the undermould, it is centered by means of the oblique end faces 16 and 15, in order to prevent a partial joint displacement. Those end faces 16 and 15 must not necessarily extend over the whole circumference of the number 4 or of the undermould 3, but can be distributed, even in an irregular manner, over the circumference of the member. By closing the mould the bellows are pressureless and the uppermould is brought down towards the undermould. Due to the profile in the ring and in a part of the undermould, a cavity 9 will be formed around the border of the element 1 to be encapsulated. That cavity, which is connected to the buffer 12, is provided in order to form a ring of elastomer, for example polyurethane elastomer, around the circumference of the sheet of shaped element by injecting said moulding substance, for example, a liquid reactive polyurethane mixture, into that cavity. When the whole circumference of that shaped element has to be encapsulated, the cavity extends along the whole circumference. When only a part of the element has to be encapsulated, either the ring extends only over the part to be encapsulated or the cavity extends only over a part of the ring. When the mould is closed, the bellows are blown up, for example by means of compressed gas or liquid. The bellows can be blown up to a pressure of for example 40 bars by means of oil. By blowing up the bellows a force which is equally divided over the surface of the ring, will be applied on that ring and will press it against the border of the sheet shaped element, for example a sheet of glass. By pressing the ring around the glass first the glass is pressed against the surface of the undermould. When the glass is curved and the radius thereof is not equal to the nominal radius as given by the mould, the glass will, under influence of the applied pressure, first be deformed up to the radius of the undermould. Suppose now that, particularly in point B, the average thickness of the glass is higher than the nominal thickness. Under influence of the pressure applied by the bellows on the ring, the flexible metal ring will first touch the glass in point B before the land face of the ring touches the undermould in point C. Due to the fact that the ring has oblique land faces, only the point B will first touch the glass. The pressure applied by the bellows on the ring will press the part BE of the ring against the glass. Due to the fact that an elastically deformable ring is used, the applied force will cause that ring to turn around point B until the land faces of the ring touch the undermould. Again due to the obliqueness of the land face the ring will first touch the undermould in point C. The flexible metal ring is now elastically deformed and will now closely follow the variation of the glass thickness around the edges of the glass sheet. When the average thickness of the glass is lower than the nominal thickness, the flexible metal ring will touch first the undermould in point C before the land face of the ring will touch the glass. Under pressure of the bellows the ring section will turn around point C until the land faces of the ring will touch the glass. Due to the elasticity and the deformation of the ring, it will tightly pack the glass around its edges. Along lines, which extend perpendicular to the point B, respectively C, the glass is tightly packed into the ring, irrespective of some deformations which may occur on the glass along those lines. Due to the tight packing, the liquid reactive polyurethane mixture which is injected into the cavity 9 can not leak through the contact points between the ring and the glass, thus rendering deflashing no longer necessary. If the ring is provided with longitudinal and/or transversal grooves (10) the flexibility thereof is improved, thus providing a better bending and deformation of the ring. When the bellows apply a pressure on the ring provided with grooves, those grooves will by their narrowing or extension enable a better bending of the ring around the border of the sheet of glass. The member 4 can be applied either around the whole circumference of the sheet of glass, for example in case that the sheet of glass is a windscreen of a vehicle, or around a part of the border of a said sheet of glass, for example in case that the sheet of glass is a lateral window of a vehicle the member will only be applied at one side of the sheet of glass. After that the ring has been applied on the border of the sheet shaped element, the moulding substance formed for example by a liquid reactive polyurethane mixture is injected into the cavity 9. After hardening of that substance, and when the bellows are depressurised, the uppermould is raised, removing the member 4 from the sheet shaped element. In the described embodiment the ring is fixed on the uppermould. It will be clear that the method according to the invention can also be applied when the ring and the bellows are part of the undermould.

Claims: A device for at least partially encapsulating a border of a substantially sheet shaped element (1), which device comprises a mould having at least a first part (2) and a second part (3) for pressing said element therebetween and for defining a cavity (9) around said border, said first part (2) comprising an elastically deformable contact member (4) which is slidably mounted in the first part and urging means (5) for urging said contact member (4) at least against said element (1), which device further comprises injection means for injecting a moulding substance into said cavity, characterised in that said contact member (4) is provided to be pressed by said urging means (5) against said element (1) and also against said second part (3) so as to define together with this second part (3) said cavity around said border and so as to be deformed in such a way that a tight contact is realized between said contact member (4) and said element (1). A device as claimed in claim 1, characterised in that, said member is formed by an elastically deformable metal ring. A device as claimed in claim 2, characterised in that said metal ring is a deformable floating steel ring. A device as claimed in one of the claims 1, 2 or 3, characterised in that, at least one land face of said member is somewhat oblique with respect to the element on which it is pressed. A device as claimed in one of the claims 1 - 4, characterised in that, at least one further land face of said member is somewhat oblique with respect to said second part of the mould. A device as claimed in any one of the claims 1-4, characterized in that said urging means comprise bellows (5), which are fixed on said first mould part (2), for applying a pressure on said contact member (4), which bellows extend substantially along said contact member (4). A device as claimed in one of the claims 1 to 6, characterised in that, said member is provided with longitudinal grooves (10) in a surface opposite to the one coming into contact with said element A device as claimed in one of the claims 1 to 7, characterised in that, said member is provided with transversal grooves in a surface opposite to the one coming into contact with said element. A member to be used in a device as claimed in any one of the claims 1- 8, characterised in that said member is formed by an elastically deformable element. A method for at least partially encapsulating a border of a substantially sheet shaped element (1), wherein said element (1) is inserted in an opened mould having at least a first (2) and a second mould part (3); said mould is closed by bringing said mould parts (2,3) together and an elastically deformable contact member (4), which is slidably mounted in said first mould part (2), is pressed at least against said element (1), thereby to define a mould cavity around at least a part of the border of said element (1); a moulding substance is injected in said mould cavity; said moulding substance is allowed to harden; said mould is opened; and said element (1) is removed from the mould, characterised in that while pressing said contact member (4) against the sheet shaped element (1), it is also pressed against said second mould part (3) so as to define said mould cavity by means of said contact member (4) and said second mould part (3) whereby irregularities in said element (1) along said cavity are compensated for by elastic deformation of said member (4) so that a tight contact is realized between said member (4) and said element (1).

Inventors: JOURQUIN, LUCIEN, MALFLIET, GUY
Applicants: RECTICEL
Application year: 1988
Main classification: B29C67
IPC codes: B29C33, B29C45, F16J15, B60J1, B29C70, B29L31