GB2144071A

GB2144071A - Method and apparatus for producing upholstery bodies from moulded foam

Info

Publication number: GB2144071A
Application number: GB08416997A
Authority: GB
Inventors: Josef Rouchal
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1983-08-01
Filing date: 1984-07-04
Publication date: 1985-02-27
Also published as: GB8416997D0; DE3327724A1; DE3327724C2; ZA845456B; GB2144071B

Abstract

In a method of producing moulded upholstery bodies having regions of different hardness, a mould (8) is provided with one or more separating members (6) which divide the mould into discrete portions. Differently-constituted foam-forming mixtures are introduced into discrete portions of the mould. The separating members (6) prevent the mixtures from flowing into one another at least during the first phase of the foaming. <IMAGE>

Description

SPECIFICATION Method and apparatus for producing upholstery bodies from moulded foam This invention relates to a method of producing upholstery bodies from moulded foam, (the upholstery bodies being particularly useful for vehicle seats), in which, to provide regions of different hardness, two or more mixtures of different composition are foamed side-by-side in a mould. the present invention also relates to apparatus for carrying out the said method.

In upholstery bodies,especially in the case of seat cushions and squabs, it is frequently desired to have different degrees of hardness in the central portion and in the edge or bead portions. for example, the central portion may be of lower hardness than the edge or bead portions.

Methods of moulding are known which make it possible to produce upholstery bodies from, e.g., polyurethane or latex foam, which have the aforementioned areas of different hardness.

This has hitherto been achieved by foaming-in reinforcing elements which are, for example, cut from compound foam or produced from appropriately-shaped hardffoam parts. Also, appropriately shaped metal inserts are known.

These known production methods incur considerable production expenditure and the results which can be achieved thereby are frequently unsatisfactory.

German Offenlegungsschrift No 31 o2 140 describes a method for producing upholstery bodies having regions of different hardness.

This is done by dispensing a plurality of foamforming mixtures, each mixture having a different composition, into individual zones of a mould cavity, the mixtures being so introduced that they flow towards one another and into one another in the mould and form overlapping mouldings in the form of tablike extensions and beads.

However, this method hs the disadvantage that the demarcation lines between the various portions of different hardness arise largely fortuitously, so that no exactly definable and reproducible separation can be achieved. this in turn has an unfavourable effect on the required properties of the moulded body.

The object of the invention is to provide a foamed upholstery body having regions of different hardness which can be accurately and reproducible made without undue expenditure and additional process features.

This is achieved by introducing the different foam-fforming mixtures into reception zones of a mould which are separated from one another so as to prevent the mixtures from flowing into one another, this separation of the mixtures being maintained at least during the first phase of the foaming.

Accordingly, the present invention provides a method of producing upholstery bodies from moulded foam, in which, to provide regions of different hardness, two or more mixtures of different composition are foamed side-by-side in a mould, the different mixtures being introduced into portions of the mould which are separated from one another so as to prevent the mixtures from flowing into one another, the separation of the mixtures being maintained during at least the first phase of the foaming.

The present invention also provides apparatus for carrying out the method described in the immediately-preceding paragraph, said apparatus comprising a casting mould of metal or a plastics material, said mould being provided with one or more separating members which extend upwardly from the bottom of the mould in accordance with the desired plane of separation between foamed regions of different hardness.

These separating members, which can readily be installed without ,undue expenditure, in any desired configuration and position, prevent the mixtures from flowing into one another prior to and during the first phase of the foaming, which leads to the formation of a surprisingly accurate separation between the zones of different hardness. The position and the course of the demarcation lines can be varied by changing the height of the separating members and/or by varying their configuration. Preferably, each separating member is disposed substantially vertically in the mould.

The height of the separating members is suitably in the range 10% to 70% of the depth of the mould, preferably 30% to 50% of the mould depth.

In one preferred embodiment, additional vertical members are provided in the mould at points corresponding to the transitions between the central portion and the bead portions of the moulded body. The height of these additional vertical members is small compared to that of the separating members.

In a second preferred embodiment, the mould has a substantially flat centre portion and two lateral sunken bead portions with arcuate bottom surfaces. The separating members are attached to those parts of the arcuate bottom surfaces which rise towards the central portion.

It will be seen, therefore, that adjacent regions of different hardness in the resulting moulded body will define slots corresponding to the separating members.

The moulded body will also have seam slots, corresponding to the additional vertical members, which separate the central portion from the bead portions.

The slots corresponding to the separating members are of greater depth than those corresponding to the additional vertical mem bers.

By suitable pigmentation of the mixtures of different composition, the exact separation of areas of different hardness can readily be made visible in the moulded product.

The slots in the moulded product which correspond to the separating members in the mould do not affect the upholstering of the moulded body in any way.

One embodiment of the invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings.

In the drawings: Figure 1 is a schematic sectional view of apparatus in accordance with the present invention; Figure 2 is a perspective view of a moulded body made in the apparatus of Figure 1, and Figure 3 is a section on line a-a of figure 2.

Referring now to figure 1, a casting mould 8 comprises a central portion 1 and bead portions 2 which, in comparison with the central portion, are deeper and have an arcuate bottom surface. the central portion 1 and bead portions 2 are filled with foam-forming mixtures of different composition so that the resulting moulded body will have regions of different hardness.

At the transitional points between the central portion 1 and the bead portions 2 are the additional vertical members 5. Although vertical members 5 produce, in the moulded body, a certain demarcation between regions of different hardness, the definition of said regions of different hardness is achieved by means of the separating members 6 which extend substantially vertically 'upwards from those parts of the arcuate surfaces of the bead portions 2 which rise towards the central portion 1. the separating members 6 have a height in the range 30% to 50% of the depth of the mould.

In making an upholstery body by means of the mould shown in Figure 1, differentlyconstituted foam-forming mixtures are placed into the bead portions 2 and the central portion 1. The separating members 6 prevent the interflow of the mixtures prior to, as well as in the first phase of, the foaming, which leads to a surprisingly exact definition of the zones of different hardness. The relatively small height (i.e. 30% to 50% of the mould depth) of the separating members 6 is, surprisingly, sufficient to ensure this exact separation through the entire moulded body.

Referring now to figure 2, a seat-pad 3 (e.g. for motor vehicles) has a comparatively soft seat portion 10 and, in comparison thereto, harder bead portions 9. These harder bead portions provide greatly improved support for the user especially when the vehicle is cornering.

Slots 7 are produced by means of the separating members 6. The presence of these slots 7 is not in any way deleterious after the moulded body has been covered and the slots moreover do not impair the properties of the moulded body.

The seam slots 12 which result from the additional vertical members 5 have only a comparatively slight depth.

The sectional view shown in Figure 3 illustrates the course of the demarcation lines resulting from the use of the separating mem bers, between the zones of different hardness.

These demarcation lines 11, which separate the softer central portion 10 from the harder bead portions 9, are partly predetermined by the corresponding separating members, and partly exactly developed during moulding along the remaining moulded portion. Thus, by means of the method and apparatus according to the present invention, the structure and properties of the moulded body can be predetermined very accurately.

Claims

1. A method of producing upholstery bodies from moulded foam, in which, to provide regions of different hardness, two or more mixtures of different composition are foamed side-by-side in a mould, the different mixtures being introduced into portions of the mould which are separated from one another so as to prevent the mixtures from flowing into one another, the separation of the mixtures being maintained during at least the first phase of the foaming.

2. Apparatus for carrying out the method according to Claim 1, said apparatus comprising a casting mould of metal or a plastics material, said mould being provided with one or more separating members which extend upwardly from the bottom of the mould in accordance with the desired plane of separation between foamed regions of different hardness.

3. Apparatus according to Claim 2, in which each separating member is disposed substantially vertically in the mould.

4. Apparatus according to Claim 2 or 3, in which the height of each separating member is in the range 10% to 70% of the depth of the mould.

5. Apparatus according to Claim 4, in which the height of each separating member is in the range 30% to 50% of the depth of the mould.

6. Apparatus according to any one of Claims 2 to 5, in which the mould comprises a substantially flat centre portion and two sunken lateral bead portions having arcuate bottom surfaces, the separating members being attached to those parts of the arcuate bottom surfaces which rise towards the central portion.

7. Apparatus according to Claim 6, in which additional vertical members are provided at the transitions between the central portion and the bead portions, the height of said additional vertical members being small in comparison to that of the separating members.

8. A moulded foamed body made in the apparatus according to any one of Claims 2 to 7, in which adjacent regions of different hardness define slots corresponding to the separating members.

9. A moulded foamed body made in the apparatus according to Claim 7, in which seam slots, corresponding to the additional vertical members, separate the central portion from the lateral bead portions of the moulded body,

10. A moulded foamed body according to Claim 8 or 9, in which the slots corresponding to the separating members are of greater depth than those corresponding to the additional vertical members.

11. A moulded foamed body made by the method of Claim 1.

12. Apparatus for producing a moulded foamed body, substantially as hereinbefore described, with reference to and as illustrated in Figure 1 of the accompanying drawings.

1 3. A moulded foamed body, substantially as hereinbefore described, with reference to and as illustrated in Figures 2 and 3 of the accompanying drawings.