GB2228484A

GB2228484A - Foamed component

Info

Publication number: GB2228484A
Application number: GB8929335A
Authority: GB
Inventors: Jurgen Emig
Original assignee: BBS AUTOTEILE
Current assignee: BBS AUTOTEILE
Priority date: 1989-01-21
Filing date: 1989-12-29
Publication date: 1990-08-29
Also published as: GB8929335D0; IT1238975B; ES2018993A6; IT9083308A0; IT9083308A1; FR2642003A1; DE3901769A1; JPH02229012A

Description

1 FOAMED COMPONENT This invention relates to a foamed component having

certain rigidity characteristics at the same time as low weight, which component has, at least in one of three coordinate directions, a dimension lying at least in the millimetre range.

By "component", components in the form of bars, ribs, beams, tubes or boards may be understood. Such components have the advantage that they can be mass produced, be lightweight and nevertheless have a volume, can easily be further processed, have to a certain extent a compressive strength and, within limits, also a tensile strength, can insulate heat or sound etc. One disadvantage, however, is that they can be broken relatively easily, that they crumble and have a low flexural rigidity.

An object of the invention is to specify a component of the type mentioned at the beginning which, although retaining the positive characteristics, nevertheless has substantially better stability within the expanded volume. At the same time, it is to be possible to retain the old processing techniques, that is to say that the chemical components forming the expanded volume need not be changed, that the known, for example two-part, moulds can continue to be used, that no special specifications are needed for the further processing of the components,- that no special retraining of the production staff is necessary, that nothing about the ma-chinery used has to be changed and that no special calculations, sacrifices in service life in other ways occur.

According to the invention there is provided a small-celled foamed component having certain rigidity characteristics at 2 the same time as low weight, which component has, at least in one of three coordinate directions, a dimension lying at least in the millimetre range, characterized in that at least one tangled strip with very open meshes lies in the expanded volume, in that the volume of the fillaments of the tangled strip is substantially less than the volume of the tangled strip, in that the expanded volume touches the filaments of the tangled strip at least on the greatest part of the surface of the filaments, in that the net volume taken up by the tangled strip corresponds at least to the greatest part of the expanded volume and in that the filament sections integrated in the tangled strip are neither substantially rigid nor substantially labile in their longitudial extent with respect to forces occurring during expansion.

Such tangled strips already exist as mass products on the market, even if for other areas of application. it reinforces the component quite extraordinarily and prevents crumbling. As before, the expanded volume continues to constitute the main volume. Externally, the component according to the invention can appear just like the previous components and also have the same characteristics such as paintability, machinability etc. Nevertheless, the distance of the original filament from that part-volume directly surrounding it is small. With sufficiently rigid filament sections, the tangled strip is als(not swept into the mould during injection moulding processes. On the other hand, however, since the filaments are sufficiently labile, they cannot become taut in the ultimate phase of the expansion operation and cut up the expanded volume during this phase. Even if the idividual contribution of the filament section is small, due to the large number of filament sections the effect adds up to an appreciable overall result.

Preferably at least one side of the tangled strip has, seen randomly, conical elevations which rise up from the central 3 effect that the tangled strip positions itself in the Mould itself and then, if at all, only the tips of the conical elevations touch against the later outer skin of the comDonent.

Preferably the filaments are of plastic to have the effect of saving weight. In addition, unlike metal filaments, these filaments do not rust. They can also be thicker at the same time as of even less weight ana consequently do not cut into the expanded volume as much. In addition, in terms of material, the plastic of the filament matches better the plastic of the expanded volume. with regard to the diverse object features of the invention, monofil filaments are particularly good.

Preferably the surface of the filaments is, at least over the greatest part of this surface, baked to the adjacent faces of the volume to have the effect that the filaments anchor themselves even better with the foamed volume.

Preferably the filaments are solidly connected to one another at crossing points to have the effect that the stability of the tangled strip instrinsically, and consequently also later in the component, is substantially better.

Preferably the crossing points have a spacing in the centimetre range to have the advantage that, on the one hand, an excellent openness of the tangled strip is obtained, so that the components can flow well into the mould used, and on the other hand the spacing of crossing point to crossing point is relatively small, which points in themselves indeed again represent a small anchorage point due to their crossing characteristics.

Preferably the spacing is, seen randomly, in the lowest r 1 4

Claims

centimetre range to Claim 7 have proved very successful, in particular in the case of small-celled rigid fodms.- Preferably the filaments have a thickness in the lowest centimetre range to have the effect that the correct shape of the tangled strip can still be adjusted manually. Preferably the thickness is in the tenths of a millimetre range to have the effect that even relatively small components with their relatively small dimensions in the centimetre range can be produced well. Preferably the filaments are baked until fused with one another at the crossing point to achieve the effect that the starting point of each filament is particularly solidly arranged. Preferably the tangled strID is produced by an at least partially random operation to have the effect that the tangled strip on the one hand is simple in production and on the other hand can nevertheless be produced sufficiently tangled, so that the random distribution of the f!laments in the volume is also good. Preferably the expanded volume is of thermoset material and is suited particularly well for components in the field of vehicle construction, such as for example spoilers on vehicles, dirve-under protection for trucks, surfboards, boat hulls etc. Preferably the filaments are of thermoset material to have the effect of providing a component which is particularly insensitive to heat. Preferably the filaments are of thermo-plastic material to have the effect that the component could subsequently be 1 further bent, provided that the expanded volume is likewise thermoplastic. Preferably a tensile force-absorbing reinforcing mat -I ies in at least one outer skin region of the expanded volume to have the effect of further substantially increasing the rigidity of the component, the load- bearing capacity of its ski, because, after all, then the tangled strip forces the reinforcing mat to lie very far away from the neutral axis. Preferably the reinforcing mat is a glass fibre mat which is substantially thinner than the component perpendicular to the glass fibre mat is thick to have the effect that the above mentioned characteristics are obtained to an extraordinarily high degree in a cheap way. However, if the price is not all that important, more expensive reinforcing mats, such as for example carbon fibre mats, can be used. Preferably a reinforcing mat is provided in two mutually opposite outer skin regions and in that the spacing between the reinforcing mats is substantially smaller than their transverse dimension to have the effect that the component is equally flexurally rigid in both directions. The invention may have the shape of a board. After all, a board has the characteristic that it is thin in relation to its width and that its length is at least comparable in relation to its width. Preferably fastening means are seated firmly with their rooting region in the component to have the effect that the fastening means can be rooted extraordinarily well and the forces occurring in the rooted region can be absorbed well. This provides substantially better results than if the fastening means are merely anchored in the expanded volume. 6 Preferably the rooting region is seated in the tangled strip to have the effect of further increasing these advantages and of then making it possible. if appropriate, to make the fastening means thinner. Preferably the fastening means are pin-like means such as screw bolts etc. to have the effect that the component can be connected easily to other subassemblies. Preferably applied around the component is a layer which is integrally bonded to the component to achieve the effect of a better printability with inks, if appropriate, and possibly a greater softness, so that injuries are rulea out more. Preferably the layer is rigid foam rubber to allow further processing of the component, for example as an air deflecting device on motor vehicles, and it is only necessary here to work with two moulds. The invention is suitable in particular for use as a wina deflecting device for vehicles. Preferably the invention comprises a tangled strip, on the one side of which there lies a reinforcing mat, is placed into a two-part mould and the gate of the mould lying at a point in front of the tangled strip which is free from the reinforcing mat so that the component can be produced in a single mould, if appropriate together with the fastening means. The apparatus need not be changed with respect to the previous designs. Preferably the gate lies tangentially to the course there of the 'reinforcing mat to achieve the effect that the jet of the injected liquid mixture does not hit or scarcely hits the reiforcing mat. 1 7 Preferably a tangled strip is placed in the open mould ot a two-part mould, which strip fills the mould at least substantially, in that a reinforcing mat is placed in the open mould, up against the tangled strip but in such a way that the.gate of the mould remains free, in that foamforming components are introduced into the mould and in that the mould is kept closed at least until the end of the expansion operation to achieve a special, simple process for the production of a component according to the invention. It is consequently not necessary to hold the reinforcing mat in any special way. If no importance is attached to the action of the tangled strip and it is assigned only a holding function for the reinforcing mat, it does no harm if the tangled strip changes during the course of the expansion operation in its final phase, such as for example fully or partially dissolves. The invention is now described with reference to a A 8 preferred exemplary embodiment. In the drawing: Fig. 1 shows, on a scale of 1:1, the plan view of a tangled strip, Fig. 2 shows the view according to the arrow 2 in Fig. Fig. 3 shows the view according to the arrow in Fig. 3, Figs. 1, 2 and 3 on a scale of 1:1, Fig. 4 shows a very greatly enlarged, broken-away cutout of filament sections and crossing points, Fig. 5 shows a diagrammatic cross-section through a two-part mould, Fig. 6 shows the view according to the arrow 6 in Figure 5, Fig. 7 shows a very greatly enlarged, broken-away cross-section from the baking region between a filament and a part of the expanded volume, Fig. 8 shows a cross-section through a two-part mould, in which the product from the f irst mould is further treated, Fig. 9 shows a diagrammatic cross-section through a tangle of filaments with a reinforcing mat placed around them for the production of a barshaped component. According to Fig. 1, a strip 11 consists of a tangle of a large multiplicity of filaments 12. 13, 14. The latter are monofil. smooth at their surface and 0.6 mm thick. The rigidity of the strip 11 is such that it can be bent off slightly in the longitudinal direction. In the transverse direction, it can be compressed manually to about two-thirds of its original height. but then springs back into the initial position. The filaments 12. 131 14 etc form numerous meshes 16. The filaments 12, 13, 14 etc are bonded at various stages of the fusion at contact points. Fig. 4 shows a complete fusion 17,, in which the entire volume of the filament 12, 13 is integral in the region of the fusion 17. In the case of the fusion 18, a bend 19 is weldnd on by its elbow region to the filament 12. Between the fusion 17 and the fusion 18. the filament c 9 i A 12 has a filament section 21. The filament 13 between the fusion 17 and a further contact point/crossing point Of another filament also nas such a filament section. The same also applies to the filament 14 and other filaments. Fusions can also form in which filaments lie tangentially against one another, where three or four filaments cross one another, fused to a greater or lesser extent. The arrangement of the filaments 12, 13, 14 etc, of the meshes 16 etc and of the fusions 17, 18 is random, if not absolutely haphazard. Indeed, it can be recognised from Fig. 1 what openness the meshes 16 have in this direction and, according to Figs. 2 and 3, in the other direction. Seen overall, the filaments 12, 131 14 etc. the meshes 16 etc and the fusions 17, 18 are evenly distributed, even if this does not apply to the individual case. The free length of a filament section 12 lies in the range of one centimetre and is likewise randomly distributed. According to Fig. 2, in this view a thickening 22, which decreases upwards and downwards, occurs in the case of the filaments 12, 13, 14. Already in the view of Fig. 2 it can be recognised that the strip 11 has, in the downward direction, conical elevations 23, which leave clearances 24 between them. In the 45' view of Fig. 3, these conical elevations are directly one behind the other. on the underside of the strip 11, the conical elevations 23 are thus not arranged randomly but according to a grid pattern and, as when driving past a vineyard with vine stakes,, one sees at one instant the clearances 24 and at the other instant clearances 26. According to Figs. 2 and 3. the strip 11 has randomly distributed crests 27 on the upper side and crests 28 on the underside. These do not, admittedly, all lie at the same level. Nevertheless. an averaging plane 29 can be passed through the crests 27 and an averaging plane 51 can be passed through the crests 28. With regard to the article to be produced, these planes 29..l are parallel. but may diverge or else form two-dimensional or threedimensional planes in the case of the production of other articles. With regard to a spoiler to be produced, the 1 spacing of the planes 29, 31 is about 1.5 cm. A strip 11 exists as a finished article on the market, to be precise under the designation Enkamat 7020/1 from the company Industrial Systems BV Velperweg NL-Arnhem As body, like the strip 11, bodies produced in another way may also be used, for example such bodies which have a tangle similar to a plastic pot-scraper or the like. According to Figs. 5 and 6, a diagrammatically represented injection mould 32 has a lower half 33 and an upper half 34, which are separated by a parting line 36. According to Fig. 5, on the left a sprue piece 37 is provided with a gate 38. In the injection mould 32, a cavity 39, corresponding to the shape of the article to be produced, is provided. The upper half 33 has a through-hole 41,, sealed-off in a way not shown, for a screw bolt 42. On the bottom of the lower half 33 there lies a glass fibre mat 43. cut appropriately to size. In its left region, it is bent upwards with a length 44, which does not however reach as far as the gate 38. On the glass fibre mat 43 lies the strip 11, which is only diagrammatically represented here. In the middle of the strip 11 there is an anchoring head 46 of the screw bolt 42. On the upper side of the strip 11 lies a second glass fibre mat 47. which also bears against the inner lower wall of the upper half 34 and is also pressed against it there because the height of the strip 11 is slightly greater in the untensioned state than in the closed state of the injection mould 32, because the cavity 39 is slightly less high than the height of the glass fibre mat plus height of the strip 11 plus heigt of the glass fibre mat 47. In alignment with the through-hole 41, there is a hole 48 provided in the glass fibre mat 47. through which hole screw bolt C passes. On the left, the t 7 m 11 ( A I 1 1 f 1 I i 1 1 1 glass fibre mat 47 is bent off into a downwardly pointing length 49, which ends however before the gate 38. As Fig. 5 shows, the crests 27, 28 - here drawn exaggerated press into the glass fibre mats 43, 47 - seen randomly. Although the components to be expanded are shot through th gate 38, the glass fibre mat 43, 47 remains in place and consequently is at a maximum distance from the neutral zone, which in the drawing goes through the parting line 36. The essential function of the strip 11 is thus to hold the glass fibre mats 43, 47 in place, in particular during injection. The liquid to be expanded can distribute itself virtually unhindered in the cavity 39, because although the strip 11 on the one hand has an excellent openness, on the other hand it is sufficiently rigid to brace itself in the cavity 39, to be precise at an extraordinarily number of points. such as the crests 27, 28 and its longitudinal section and cross- section. Finally, random pretensioning is carried out in the expansion operation. Many filament sections 21 after all lie more or less perpendicular to the expansion movement of the expanding volume. The foam is always more viscous and doughy at the end, in terms of time, of the expansion operation and in this operation takes with it filament sections 21. so that the latter stretch more. Even if, seen for itself, the individual filament section 21 only provides a small contribution, the overall contribution due to the many filament sections nevertheless remains considerable. As Fig. 6 shows. the length 44, 49 is provided around the gate 38 with a cut-out 51, 52, so that the gate 38 never has glass fibre mat 27 directly in front of it. To the right and left of it, in a region 53, 54, the lengths 44, 49 touch each other or even overlap. However. it is also possible to dispense with such lengths 44, 49, as shown on the right in Fig. 5, to be precise because - if the article to be produced has the shape of a board 56 which is loaded upwards or downwards according to the arrow 57 in Fig. 8 - rigidity in or around the neutral axis 12 scarcely matters, if at all. If the board 56 produced in a mould according to Figs - 5 and 6 is cut, randomly distributed and randomly shaped cross-sections 58, inlets 59, longitudinal sections 61 of the filaments 12, 13, 14 etc appear in the cut surface. According to Fig. 8, the board 56 is introduced into a second injection mould 62, of known shape. It has a parting plane 63, a sealed through-hole 64 for the screw bolt 42 and a sprue piece 66. Since the board 56 is smaller in all dimensions by a gap 67 than the cavity 68 of the injection mould 62, the board 56 can be sheathed with a further layer, for example with a softer foamed material, with differently coloured materials, with printable materials or the like. Consequently, the expanded volume 69 is enveloped together with the glass fibre mats 43. 47. Tests have shown that the strip 11 does not by any means have to be clamped between the halves 33, 34. Rather, it suffices if there is still a considerable distance here from the underside of the upper half 34. It suffices to place the glass fibre mat 49 simply onto the strip 11, the crests 27, 28 not penetrating of course. Contrary to all expectations, the glass fibre mats 43, 47 are nevertheless not swept into one corner of the injection mould 32 and entangled there. Rather, this configuration remains lying in the cavity 39. By the expansion operation - it has been found the glass fibre mat 47 can be raised to over half its original height. The only condition is that the gate 38 remains free with regard to the glass fibre mat region. According to Fig. 9, one has a circular-cylindrical strip 71, which likewise consists of many filamentsi is likewise open, has an adequate but not excessive rigidity and around which there lies a glass fibre mat 72. At the place where the injection jet 73 comes in, a free point 47 is provided. The entire assembly is, of course, surrounded by a mould.

1 13 i i It is clear that other articles, such as boat hulls, pipes, T girders, U supports, channel-shaped structures etc can also be produced in this way.

Wherever importance is attached to the reinforcing characteristics which the strips 11. 71 can yield with suitable material selection, it is advantageous if the filaments have - which is shown for example on the filament 12 - a baking region 76 with the expanded volume 69. Depending on choice of the process and material parameters, such as fusing characteristics, chemical solubility, temperature or the like, the baking region 76 may be more or less intensive.

14 CLAIMS 1. Small-celled foamed component having certain rigidity characteristics at the same time as low weight, which component has, at least in one of three coordinate directions, a dimension lying at least in the millimetre range, characterized in that at least one tangled strip (11, 71) with very open meshes (16) lies in the expanded volume (69), in that the volume of the filaments (12, 13, 14. etc.) of the tangled strip is substantially less than the volume of the tangled strip (11),, in that the expanded volume (69) touches the filaments (12, 13, 14, etc.) of the tangled strip (11, 71) at least on the greatest part of the surface (74) of the filaments, in that the net volume taken up by the tangled strip (11, 74) corresponds at least to the greatest part of the expanded volume (69) and in that the filament sections (21) integrated in the tangled strip (11. 74) are neither substantially rigid nor substantially labile in their longitudinal extent with respect to forces occurring during expansion.

2. Component according to Claim 1, characterized in that at least one side of the tangled strip (11. 74) has. seen randomly, conical elevations (23) which rise up from the central region (22) of the net volume of the tangled strip (11. 74).

3. Component according to Claim 1g characterized in that the filaments (12. 131 14. etc.) are of plastic.

4. Component according to Claim 1 or 3. characterized in that the surface (74) of the filaments (12. 13r 14f etc.) is. at least over the greatest part of this surface (74), baked to the adjacent faces of the volume (69).

1

5. Component according to Claim lt characterized in that the filaments (12, 13, 14, etc.) are solidly connected to one another at crossing points (17. 18).

6. Component according to Claim 5, characterized in that the crossing points (17, 18) have a spacing in the cetimetre range.

7. Component according to Claim 6, characterized in that the spacing is, seen randomly, in the lowest centimetre range.

8. Component according to Claim 1, characterized in that the filaments (12. 13r 14. etc.) have a thickness in the lowest centimetre range.

9. Component according to Claim 8, characterized in that the thickness is in the tenths of a millimetre range.

10. Component according to Claims 3 and 5, characterized in that the filaments (12, 13.. 14,. etc.) are baked until fused with one another at the crossing point.

11. Component according to Claim 1, characterized in that the tangled strip (11,. 71) is produced by an at least partially random operation.

12. Component according to Claim 1, characterized in that the expanded volume (69) is of thermoset material.

13. Component according to Claim 3, characterized in that the filaments (12. 131 14, etc.) are of thermoset material.

14. Component according to Claim 3, characterized in that the filaments (12, 13, 14, etc.) are of thermoplastic material.

15.. Component according to Claim 1, characterized in that a tensile force-absorbing reinforcing mat (43. 72) lies in at least one outer skin region of the expanded volume (69).

16. Component according to Claim 15. characterized in that the reinforcing mat (43. 72) is a glass fibre mat which is substantially thinner than the component (56) perpendicular to the glass fibre mat (43. 47) is thick.

17. Component according to Claim 15 or 16. characterized in that a reinforcing mat (43. 47) is provided in 16 two mutually opposite outer skin regions and in that the spacing between the reinforcing mats (43, 47) is substantially smaller than their transverse dimension.

18. Component according to Claim 17, characterized in that having the shape of a board (56).

19. Component according to one or more of the preceding claims, characterized in that fastening means (42) are seated firmly with their rooting region (46) in the component (56).

20. Component according to Claim 19. characterized in that the rooting region (46) is seated in the tangled strip (11).

21. Component according to Claim 19, characterized in that the fastening means (42) are pin-like means such as screw bolts etc.

22. Constructional unit according to one or more of the preceding claims, characterized in that applied around the component (56) is a layer which is integrally bonded to the component (56).

23. Constructional unit according to Claim 22. characterized in that the layer is rigid foam rubber.

24. Constructional unit according to Claim 23, characterized in that it is a wind deflecting device for vehicles.

25. Apparatus for the production of a component according to one or more of Claims 1 to 21 characterized in that a tangled strip (11,, 71),, on the one side of which there lies a reinforcing mat. is placed into a twopart mould (34) and in that the gate (38) of the mould lies at a point in front of the tangled strip (11.. 71) which is free from the reinforcing mat (43. 471 72).

26. Apparatus according to Claim 25. characterized in that the gate (38) lies tangentially to the course there of the reinforcing mat (43, 47).

27. Process for the production of a component according to one or more of the preceding claims, characterized in that a tangled strip (11r 71) is placed in the open mould (32) of a two-part mould (33, 34), which strip fills the mould (32) at least substantially. in that a t 17 reinforcing mat (43,47,72) is placed in the open mould (32), up against the tangled strip (11,71) but in such a way that the gate (38,74) of the mould remains free, in that foamforming components are introduced into the mould (32) and in that the mould (32) is kept closed at least until the end of the expansion operation.

28. Small-celled foamed component as claimed in claim 1 substantially as described with reference to the accompanying drawings.

29. Process for the production of a component substantially as described in any of the examples of the invention disclosed herein.

Published 1990 atThe Patent =ce. State House. 66 71 High Holborn. London WC1R 4TP. Further copies maybe obtalnedfrom The Patent=ice. Sales ch, st mary Cray. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent. Con. l!S7