EP0073118A2

EP0073118A2 - Improvements in or relating to the manufacture of spring mattresses

Info

Publication number: EP0073118A2
Application number: EP82304177A
Authority: EP
Inventors: Luigi Santarini
Original assignee: Permaflex SpA
Current assignee: Permaflex SpA
Priority date: 1981-08-20
Filing date: 1982-08-09
Publication date: 1983-03-02
Also published as: IT1167961B; IT8109496A0; EP0073118A3

Abstract

A spring mattress has a structure including a spring carcass (1) on each face of which there is disposed a composite layer including a fiber padding layer (3), an intermediate foamed layer (5,24A,24B) and a felt padding layer (7), the whole of which is disposed in a cloth cover (9). The foamed layers (5) are formed by introducing the reactant materials into a laminar space defined between the respective padding layers (20,22,3,7) and dividing the foamed layer (24) so formed to separate the respective composite layers. An apparatus for forming the mattress includes two endless conveyors (11,13) for feeding the padding layers (20,22,7) which together define a laminar space in which the foamed layer (24,5) is formed, and a nozzle device (19) to inject into the laminar space the reacting components which form the foam.

Description

The present invention relates to methods and apparatus for manufacturing spring mattress.
Conventional spring mattresses comprise a metal carcass formed from a plurality of springs suitably connected together, and on the faces of the carcass a plurality of outer layers mainly consisting of one padding layer of felt or an equivalent material and at least one fibre layer, typically mostly cotton or wool, and generally also an intermediate layer of expanded elastic material, typically flexible expanded polyurethane cut from a block. These mattresses are mounted with the said layers being connected together perimetrally, the connection possibly being completed by tie elements which pass through the mattress assembly and may be fixed by means of buttons. In all cases, the connection between the various layers is. weak, and the layers are subject to relative sliding and rapid deterioration.
The problem which is to be solved relates to the provision of a more rational, simple and stable fixing of the spring mattress components which preferably provides a satisfactory result with relatively low-cost materials, in particular with regard to the padding layers.
The present invention provides a method of manufacturing a spring mattress which includes a spring structure and a composite layer disposed against each face of the spring structure, each composite layer including at least one padding layer and including a foamed layer disposed adjacent the or at least one of the padding layers
characterised in that
the method comprises the steps of defining a laminar space at least partly by at least one padding layer which is to lie adjacent the foamed layer in the finished mattress, and introducing into said laminar space and reacting therein component materials which react together therein to form said foamed layer.
In this manner, as the foamed material is produced, a layer of this material forms and normally becomes substantially continuously bonded to the adjacent layer which will lie adjacent the foam in the finished mattress.
Because of the fact that the foaming reaction causes some pressure against the surfaces which define the space to be filled with the foamed material, and as the reacting components will normally remain to some extent fluid during at least part of the reaction, a certain penetration of the adjacent padding layer takes place, the foamed material thus becoming bonded to the layer against which the foamed material is formed. This gives greater cohesion and improved stability of the layer against which the foam makes contact. In particular, where the padding layer is felt, stability and cohesion, and therefore resistance to wear and tear are increased, even if the felt is of poor quality, without the need for special arrangements such as a mesh or other reinforcement inside the felt.
Preferably the laminar space is defined by two layers which are used in the formation of the mattress. These two layers can desirably be the two layers which are required to lie adjacent opposite faces of the foamed layer, for example a felt padding layer and a fibre padding layer of cotton, wool or the like. In this case the three layers thus formed and bonded together are used as the composite assembly for mounting on the face of the spring structure of the mattress between the mattress and the covering, this latter being possibly bonded to a light foamed reinforcement layer or connected by buttons.
Alternatively, the said two layers defining the laminar space may be bonded by the reacting step to a layer of foamed material which has a thickness greater than that required for the foamed layer of a single composite layer, said foamed layer then being split longitudinally in an intermediate position. In this case, two composite layers can be formed by a single foaming operation, with the advantage that the foamed material layer can be of double the necessary thickness required for the formation of a mattress face. In such a case, a fibre padding layer of cotton, wool or the like can be joined to the cover, for example by quilting, and the combined layer of felt and foam plus the combined layer of covering and padding are then mounted on each mattress face.
The invention further provides an apparatus for forming a composite material comprising a foam layer and at least one adjacent padding layer for use in the manufacture of spring mattresses characterised in that the apparatus comprises two endless conveyors each having a portion which faces and is disposed parallel to the portion of the other conveyor to define therewith a laminar space, means for continuously feeding a padding layer to at least one of said portions, means for injecting components into said laminar space which react together to form said foam layer, and means for defining longitudinal side faces of the laminar space to -define the side faces of said composite material.
Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a diagrammatic sectional view of a spring mattress structure;
Figures 2 and 3 show two types of composite layers which can be used in-the structure of Figure 1; and
Figure 4 is a schematic sectional view of apparatus for forming the composite layers.

In the Figures, the reference numeral 1 indicates overall the metal carcass or spring structure for forming the mattress. It is flanked on each face by a composite layer including a layer 3 of felt or like padding material which is in contact with the metal parts. The composite layer also includes a layer 5 which is of foamed material, for example flexible polyurethane, adjacent the felt padding layer. A fibre padding layer 7, which can be natural fibre such as wool or cotton, is disposed next to the foamed layer to complete the composite layer. The assembly of spring structure 1 and composite layers is enclosed in a fabric covering 9, which may also be bonded to a thin foamed reinforcement layer.
The composite layers can be created by bonding together the layers 3 and 5 or the layers 3, 5 and 7, by utilising the reaction for forming the foamed layer 5. Figure 2 show two composite layers which are produced simultaneously and then separated by splitting the single layer of foamed material along the faces 5A in order to divide the continuous material into two composite layers. Figure 3 shows a composite layer formed from a felt layer 3, a foamed layer 5 and a fibre padding layer 7, which are bonded together by the localised foam of the layer 5 between the two padding layers 3 and 7.
Figure 4 shows a horizontally extending apparatus for forming such composite layers. The reference numerals 11 and 13 indicate two endless conveyors formed fromhinged slats or other means, of which the two opposing, parallel active branches or portions can be kept at a predetermined distance apart,to define a laminar space therebetween, by reaction means which can either be in the form of slide guides which merely extend along the edges of the active branches, or can comprise intermediate structures with rollers 15 and/or reaction walls 17. The reaction means is provided to resist deformation of the portions of the conveyors due to pressure exerted on said portions by the reacting component material during the foaming reaction.
The reference numerals 20 and 22 indicate the two padding layers to be bonded to the foamed layer during the foaming reaction. These two layers are fed along respective ones of the active branches of the conveyors 11 and 13, and can for example be two similar layers of felt, or one a layer of felt padding whilst the other is a layer of fibre padding. The reference numeral 19 indicates a feed nozzle which can either be a single feed nozzle or one of a bank of such nozzles making up injecting means for the components of the foaming reaction. The injecting means can either be fixed or driven with reciprocating translatory motion transversely to the direction of movement of the active branches of the conveyors 11 and 13. In all cases,the arrangement is such as to create a substantially uniform injection of components into the laminar space in order to continuously form the foamed layer 24 in the laminar space between the active branches of the two conveyors during movement of the conveyors. At the exit end of the conveyors there is produced a material formed from layers which are bonded by the effect of the adhesion and cohesion between the layers 20 and 22 and the layer 24. Figure 4 shows a knife 26 which can cut, i.e. split, the layer 24 in order to form two composite layers 20, 24A and 22, 24B respectively, which can either be two identical composite layers such as the aforesaid composite layer 3,5 (Figure 2) , or different composite layers. If the knife 26 is dispensed with and the thickness of the layer 24 is reduced, then by feeding a felt layer 20 such as the layer 3, and a padding layer 22 such as the layer 7, a composite layer 3,5,7 is obtained as shown in Figure 3.
If it is found necessary and advisable to provide means for retaining the layer 22 against the conveyor 13 along the active branch (i.e. should it be considered unsafe to rely on the pressure of the foamed layer during the foaming reaction), pins or pointed projections can be provided on the slats of the upper conveyor 13 which are of suitable shape for withdrawing from the layer 22 at the exits, or alternatively a suction effect can be provided by way of suction elements disposed along the active branch of the conveyor 13.
Figure 4 shows an apparatus in which the laminar reaction space is horizontal, but a different orientation of said space, including inclined or vertical, is also possible.
If the endless conveyors are in a non-horizontal position, and particularly if vertical or inclined, feed of the padding layers can take place from below with upward movement or vice versa.
In order to control the degree of impregnation of the felt layers by the initially liquid reacting components - apart from choosing a suitable degree of inclination to the horizontal - the surface of the padding layers 20,22 can be treated, and/or the reaction components can be given a suitable viscosity.
The apparatus also includes means for defining the longitudinal side faces of the laminar reaction space substantially in positions corresponding with the side edges of the layers to be bonded to the foamed material layer being formed to define side faces of the resulting composite material. Such means may be made of strips of disposable material, or endless annular tapes with their surfaces adjacent the laminar space siliconed or otherwise made anti-adhesive, or comprise the bent bver edges of one or both padding layers, for example the bent up edges of the lower layer. It will be appreciated that the. side faces may also be defined by other means.

Claims

1. A method of manufacturing a spring mattress which includes a spring structure (1) and a composite layer (3,5,7,20,22,24A,24B) disposed against each face of the spring structure, each composite layer (3,5,7,20,22,24A,24B) including at least one padding layer (3,7) and including a foamed layer (5,24A,24B) disposed adjacent the or at least one of the padding layers (3,7;20,22)
characterised in that
the method comprises the steps of defining a laminar space at least partly by at least one padding layer (20,22,3,7) which is to lie adjacent the foamed layer (5,24A,24B) in the finished mattress, and introducing into said laminar space and reacting therein component materials which react together therein to form said foamed layer.

2. A method as claimed in claim 1, characterised in that the viscosity of the reaction component materials and/or the permeability of the padding layer(s) (20,22,3,7) are regulated in order to control impregnation of the component materials into the padding.

3. A method as claimed in claims 1 or 2, characterised in that the laminar space is defined by two layers (3,7) which are to lie adjacent opposite faces of the foamed layer (5) in a single said composite layer.

4. A method as claimed in claims 1 or 2, characterised in that the laminar space is defined by two layers (20,22; 3,3) which are bonded by the reacting step to a layer of foamed material (24) which has a thickness greater than that required for the foamed layer of a single composite layer, said foamed layer (24) then being split longitudinally in an intermediate position.

5. A method as claimed in claim 4, characterised in that the method further comprises the step of joining a cloth cover (9) to a fibre padding layer (7) and joining this to the composite padding and foamed layers (24A,24B, 5,20,22,3).

6. An apparatus for forming a composite material comprising a foam layer (24) and at least one adjacent padding layer (20,22) for use in the manufacture of spring mattresses
characterised in that
the apparatus comprises two endless conveyors (11,13) each having a portion which faces and is disposed parallel to the portion of the other conveyor (11,13) to define therewith a laminar space, means for continuously feeding a padding layer (20,22) to at least one of said portions, means (19) for injecting components into said laminar space which react together to form said foam layer, and means for defining longitudinal side faces of the laminar space to define the side faces of said.composite material.

7. An apparatus as claimed in claim 6, characterised by means for driving said injecting means (19) in reciprocating motion transverse to the direction of motion of the conveyors (11,13) to inject said components substantially uniformly across the width of the laminar space.

8. An apparatus as claimed in claim 6 or 7, characterised in that the portions of the two conveyors (11,13) extend horizontally, and means are provided for ensuring proper positioning of a padding layer fed to an upper one of the conveyors such that this layer makes contact with said portion of the upper conveyor.

9. An apparatus as claimed in claim 8, characterised in that the positioning means comprise suction means, pins or pointed projections.

10. An apparatus as claimed in any one of claims 6 to 9, characterised by comprising means (15,17) for ensuring the necessary reaction against the two facing portions of the conveyors (11,13) in order to obtain resistance to deformation due to the pressure which the reacting components can exert on the portions of the conveyors (11,13).