EP0494839A1

EP0494839A1 - A bedstead of springs made with compound materials

Info

Publication number: EP0494839A1
Application number: EP92500001A
Authority: EP
Inventors: Alfonso Solans Serrano
Original assignee: Pikolin SA
Current assignee: Pikolin SA
Priority date: 1991-01-08
Filing date: 1992-01-02
Publication date: 1992-07-15
Anticipated expiration: 2012-01-02
Also published as: EP0494839B1; ES2027569A6; DE69204306T2; ATE126985T1; DK0494839T3; IE69272B1; GR3018112T3; ES2046153A6; IE920041A1; DE69204306D1

Abstract

A bedstead of springs made with compound materials in which such springs are formed from a special, fibre reinforced plastic material section taking up an inverted "U" shape, with short vertical sides converging inwards with a 45^o bevel half-way up; the invention also comprises bushes (11) for fitting to a bedstead frame (10). These bushes match the shape of the section and are provided with thick laterally emerging lugs (5). Supplementary, hollow, bottomless caps (12) in the form of a truncated parabola in plan, having interior guide ribs (6), two of which have longitudinal projections (7) along which the spring section slides and is held complete the assembly. These caps are partially closed off at their widest end via two small bush lug supporting end pieces (8) which house and hold the bush lugs (5); likewise, the bedstead has strengthening regulator made up of rigid, prismatic-rectangular shaped elements which are hollow (13) right through with a cross section matching the section of the springs (9) on which they can slide.

Description

This Patent of invention refers to a bedstead formed by a succession of transversal springs fitted on a frame structure. Apart from others which we shall be seeing later, this bedstead offers the special feature of its springs being made from fibre reinforced plastic materials.
Amongst the highly varied types of bedstead, those in which the functional area is formed by a series of wooden springs provided with extraordinary qualities of strength and flexibility are known in the marketplace. They offer optimum adaptation for supporting the mattress and, consequently, the person using the bed. This is why these bedsteads are so widely used, so much so that it may be stated with no doubt at all that, at the present time, they are the ideal mattress base most accepted both by users and merchants, in the manufacturing industry and even by health authorities.
The excellency of the aforementioned wooden spring bedsteads is grounded, as we have said, on the qualities of the springs' strength and flexibility but it is precisely these points where the problems and disadvantages that these products suffer from lie.
In fact, for springs to act as such, it is necessary to follow a laborious manufacturing process since they are made up of a package of thin wooden strips, duly compacted and given a slight arching effect. With wood being their basic, main component, it is easy to understand that the springs are significantly affected by weather conditions such as environmental humidity, temperatures, etc., despite the fact that, in better quality bedsteads, these springs are given a plastic protection which, apart from contributing towards raising the price of the product, also has the disadvantage of breaking because of friction or other unforeseeable causes, thus leaving the springs' wooden component uncovered. They would then unfailingly deteriorate in their functionality as time elapses.
On the basis of the prestige acquired by the aforesaid spring bedsteads, several different types have appeared in the marketplace in which endeavour has been made to avoid the laborious manufacture of the springs which have been replaced by simple cross-pieces or rigid wooden slats with which flexibility, such a determining feature of this piece of furniture, disappears, or endeavour has been made to replace the wooden springs by springs made of other materials which would provide a certain degree of flexibility, with the idea of lowering the price of the product and preventing its possible deterioration. Endeavours have also been made along these lines using metal rods and sheet, plastic materials and even combining metals with plastic.
Thus, in current state-of-the-art, we find forerunners of bedsteads made up of cross pieces of various widths obtained from simple, compact, rigid wood as well as other designs of flexible springs either made up simply of coated metal rods or metal rods supplemented by metal flat strips or metal rods or strips coated with plastic materials or, finally, by springs made with a complex structuring of areas and ribs obtained wholly with plastic materials.
Despite the various, praiseworthy attempts referred to in the foregoing paragraph, none have managed to compete in qualities with genuine wooden springs and the truth is that nobody has triumphed in this attempt.
The applicant for this Patent, who has a singular experience in this type of manufactured product through being the leading Spanish firm in spring bedstead manufacturing, is fully aware of the disadvantages that wood brings to his products and of the possible advantages that replacing wood by synthetic plastic materials could bring to his product, as a natural consequence of the physical-chemical and mechanical properties intrinsic to this kind of material.
Based on this possibility, quite some time ago, the applicant commenced profound research directed towards replacing wooden springs by sections made in plastic materials. These sections had been conceived in such a way that, whilst enjoying all the advantages inherent to the very nature of the material employed, mechanical performance and the material's behaviour on being used to make a bedstead's functional surface were at least as effective as those provided by the wooden springs which it was intended to replace. With this in mind, it was laid down that the section to be obtained would have to behave elastically in the same way as the aforementioned wooden springs, that its elastic hysteresis were less and that, finally, it would be totally stable to weather conditions.
Having initially discarded complex shape structures and metal frameworks, efforts along this line of research were directed towards achieving a type of section with a simple, adequate format sufficiently reinforced by a continuous synthetic fibre support. It would be a section which could be obtained from different thermostable plastics.
To obtain the section required, an analysis was first made in order to find out the exact stresses in quality and quantity that each area of the lamina in a bedstead is supporting. This study managed to prove that 96% of the stresses are bending and 4% compressive in nature.
As a result of the research, work and tests carried out, the spring bedstead, the subject matter of this Patent, was obtained, in which three fundamental components are distinguished, made up, in fact, of the section itself, which is actually the spring, the bushes for fitting them into the bedstead's frame and supplementary caps perfecting the spring-to-bush assembly which, in turn, contribute towards the mattress being stable on the bedstead.
The section, which is the spring itself, is characterized by having an inverted "U" shaped cross section and short vertical arms compared to its broad horizontal stretch, and said vertical arms, at a point nearly halfway up, converge inwards with respective 45° angles providing the section with bevelled longitudinal edges; this section can be obtained from flat, crimped, woven, combed or braided fibres or a combination of them; by subsequent injection onto them in a suitable press-mould of any type of thermostable plastic material such as ortho- and isophthalic poliesters or any other equivalent, either alone or with various organic and inorganic charges such as calcium phthalate, calcium carbonate, talc or others and, during the process, adding small amounts of other materials such as fabrics, threads, plastic films with a minimum thickness or paper which, apart from influencing the section's behaviour, participate in the outside, decorative finish of the spring; proportions of 70% fibre to 30% isophthalic resin or plastic are foreseen and, to the effects of the deflection required in the spring's body as a function of its length for different sizes of bedstead, it is laid down that the section be obtained with a curvature between 4m and 9m radius.
The invention also provides for the possible addition of two narrow, longitudinal projections on the spring's functional surface, as a continuation of the bevels of its two short side faces. These projections are angular in cross section and define two thin grooves which lead to perfect adaptation of the mattress to the bedstead and prevent, it sliding, as well as respective reinforcing ribs in the centre of its inside/ underneath part.
The invention's second component relates to the bushes which fit into the bedstead's frame and house the ends of the springs, protecting them from friction and wear, since frames are usually metal and movements in the springs as a result of their bending capability must be prevented from ocurring on the frame's metal edges.
Made in plastic, these bushes have a slotted body exactly matching the spring, the end of which they receive and, at their mouth facing towards the inside of the mattress, their end side faces and bevelled edges noticeably emerge and are prolonged in thick side lugs located in a plane perpendicular to the body in an approximately square shape but with their outside vertices curved. This curvature is more marked at their respective upper vertices.
Apart from improving the aesthetics of the bedstead, the supplementary caps, also made in plastic, contribute towards improving the anchoring of the springs to the frame and towards stabilizing the mattress on the bedstead. They ire essentially shaped by a hollow body without a bottom, with a truncated parabola in plan view decreasing in height from the widest part, where it matches the bedstead's frame, to its opposite end, parallel and narrower, in which the height of this supplementary body practically matches that of the springs. At their narrowest end, which faces towards the bedstead's longitudinal centre line, these caps have a mouth coinciding in shape exactly with the section of the springs and, from this mouth, three ribs begin and extend in parallel fashion towards the inside of the cap, slightly increasing their height as the cap itself does, acting as guides and adapting to the shape of the springs which are to be located inside them. The two side ribs, which are the highest and are located on both sides of the spring, are provided on their inside edge with small longitudinal projections emerging towards the centre line of the cap and bevel shaped to hold the spring when pressure is exerted on it when fitted in the bedstead. The aforesaid three ribs do not reach the widest end of the cap so as to shape a clear space between them and small side pieces which, at this widest end of the cap, close it off and allow it to house and hold the spring receiving bush side lugs.
The elasticity required on the functional surface of each type and size of bedstead is preset by the number of springs shaping it, as well as the width and thickness of them. Therefore, coefficients of elasticity and firmness are constant parameters for each bedstead made with wooden springs.
We see, then, that these coefficients of elasticity and firmness, as well as their suitable regulating, constitute fundamental principles which must be taken into account when designing the manufacture of a structured bedstead with a base formed with such springs.
The aforementioned regulating is a further objective intended and achieved, in a very simple but effective way, by this Patent using simple means allowing individual regulation of the coefficients of elasticity and resistance of each of the various springs making up the bedstead. This regulation can be calibrated and modified at the user's will at any time he may deem fit.
The springs protected by the Patent are shaped from a special section adopting an inverted "U" shape cross section with its short, vertical arms converging inwards towards a broad horizontal stretch. The proportions of these sections vary both as a function of the size of the bedsteads on which the springs are fitted and as a function of the place each spring occupies in the bedstead's frame, since bedsteads are known where their centre springs pertaining to the areas in which the bedstead has to support greaters stresses are noticeably wider than springs located in areas near the bedstead's headboard and footboard.
The Patent also provides for the section making up each spring to be given a slight longitudinal curvature which determines the deflection defining its elastic capacity.
Whilst being used, each spring within the bedstead's framework withstands a pressure exerted by the weight of the users and, thanks to this pressure and the springs's elasticity, the spring undergoes a deformation of its initial design which is reflected both in the arc of its longitudinal curvature and in the parallelism of the short vertical sides given by the "U" cross section, the sides of which tend to diverge outwards in order to absorb the bending stresses supported by the spring, whilst totally or partially recovering its original shape as soon as the pressures being received are removed or modified by virtue of the spring's intrinsic elasticity.
From the foregoing paragraph, it can be deduced that if we limit or prevent the springs from deforming, we increase resistance to pressures and, consequently, we increase the degree of strength of the bedstead's functional surface by a corresponding magnitude.
On the basis of this principle, this Patent has provided for simple spring elasticity and strength regulating elements, each of which is made up of a totally rigid piece in a general elongated rectangular prismatic shape, which offers the special feature of having a transverse channel or hollow all the way through, also rectangular in cross section, defining openings in its long sides. Like the rest of the hollow, these side openings exactly match in size those of the section of the spring to which the regulator is tightly fitted in order to facilitate its being moved along the spring. On its shortest ends, this regulator thickens for reinforcement on both sides and thus defines concave-knurled arching effects on the outside surface which facilitate the regulator's manual sliding along the spring.
These regulators have + and - signs engraved on their top face, which is the most visible. These signs are duly aligned in the vicinity of one of its ends and when these regulators are fitted on a bedstead spring, the + sing appears on that side of the regulator facing towards the bedstead's centre whilst the - sign is located on the side nearest the bedstead's sides.
The mission fulfilled by these regulators, on tightly enveloping the springs to which they are fitted, is to prevent divergence between the narrow side faces of the springs and, thus, the latter confer greater firmness to the bedstead's surface on increasing their resistance to pressure.
Manually operated, as we have already mentioned, these regulators are arranged preferibly in pairs on each of the springs and, according to their location on them, make it feasible to set their degree of resistance.
In fact, if we locate the two regulators of the same spring in the proximity of its ends, next to the bedstead's frame where the spring is fitted and, therefore, prevented from suffering any divergent deformation of its initial state, the spring's firmness will not be changed by the action of these regulators, since the spring in question will bend under the effects of the pressures it receives and the section's structure will suffer the pertinent deformation along the rest of its length. This divergent deformation will be more marked in the central areas of said spring.
If we move the regulators towards the central area in the direction of the + signs engraved on their top, we lessen the length of the spring's deformable area and, therefore, we increase its resistance. This resistance will increase as the regulators are being moved to the most central position, where the maximum resistance which the springs can attain occurs.
In order for the invention to be better understood, a practical form thereof is shown in the adjoining drawings, as a example without any limiting scope.
Seen in cross section, Fig. 1 shows us two different sizes of the section making up the springs as envisaged in the patent. The sizes of this section will naturally adjust to the requirements and features of the bedstead it is intended to make in each case.
Fig. 2 represents the bush in which the spring ends fit in front elevation, plan and rear view, as well as a detail in perspective of this piece, making it easier to understand.
Fig. 3 shows a section of the same bush through A-A′ in Fig. 2.
Fig. 4 shows another section of the same piece cut through B-B′ in Fig. 2.
Fig. 5 shows two views of the supplementary cap seen in elevation from its widest end and seen in plan underneath without a bottom.
Fig. 6 is a section view of the same cap through C-C′ in Fig. 5.
Fig. 7 shows two views of the cap itself enabling us to see both its external configuration and its internal structuring.
Fig. 8 and Fig. 9 give us a top and underneath view of the three basic bodies making up this patent, i.e., spring, bush which receives one end of same and supplementary cap as they are all fitted and mounted on a frame to make up the bedstead assembly, which is not shown completely in the drawing as it is deemed unnecessary, since it would be no more than a mere repetition of what is defined and represented in these drawings.
Figure 10 represents in perspective a portion of a spring made in accordance with the Patent.
Figure 11 is a schematic representation of a spring seen from the side to show us its slight longitudinal curvature giving it its deflection.
Figure 12 shows us a view through A-A′ of Figure 11 when the spring is at rest.
Figure 13 is another similar view showing the spring when under pressure.
Figure 14 shows us a plan and elevation view of a spring strengthening regulator.
Figure 15 shows the same item in perspective.
Figure 16 shows a cross section through a spring coinciding with the positioning of a regulator.
Finally, Figure 17 consists of a view in top perspective of a spring with its regulators, fitted onto a bedstead frame.
In all the figures, we can see that the springs 9 are formed from an inverted "U" shaped section with short vertical arms converging inwards to form the bevel 1 joining the horizontal stretch 2 which is the spring's functional surface.
The invention has slight longitudinal projections 3 on this horizontal stretch 2 as can be seen specifically in Fig. 1. Their sole purpose is to improve the mattress's seating on the bedstead.
The figures also show us the special arrangement of the spring receiving bush 11 in which its slotted body 4, shaped to the shape of the springs, and the lugs 5 which emerge on both sides of its mouth can be seen.
Likewise, the cap 12 which, by means of its interior ribs 6 fits with the spring 9, is also shown. The spring is secured onto said ribs via the longitudinal projections 7 which emerge slightly at their bottom edge and are bevelled to face towards the cap's centre line. These projections are located on the two side guide ribs 6.
The cap's two bush lug support pieces 8, which partially close off the cap 12 at its widest end, can be seen in the drawings. Between the support pieces 8 on the caps 12 and the interior ribs 6 of this same cap we can see a small space in the figures, since the ribs 6 do not reach the end of the cap and so this small space houses and holds the lugs 5 of the bush 11 when the assembly is fitted to a bedstead frame 10 and the caps 12 anchor the springs and balance the bedstead's surface.
The drawings also show us how the springs 9, shaped in their initial structuring with deflection f, deform the parallelism of their narrow vertical sides in the manner as shown in lines BC-DE and B′C′-D′E′ when receiving pressure effects. Such deformation is conditioned and made practically impossible thanks to the action of the rigid regulator elements which fit their full length hollow space 13 to the cross section of the springs 9.
We can also see in the figures the sides of the same regulators concave in configuration and with knurling 14 to facilitate moving them by hand as well as the + andsigns engraved on their visible top face arranged so that the + sign is located on the side of the regulator facing towards the bedstead's centre line whilst thesing faces the bedstead's frame members.
The foregoing is a faithfull description of the subject matter of this Patent, in which all those variants which do not alter the essential nature of what is being claimed can be deemed as included.

Claims

A bedstead of springs made from compound materials of the type made up of a frame structure and functional surface determined by a succession of transversal springs fitted thereon, characterized by comprising three fundamental components made up by a special section of the spring (9), bushes (11) for embedding same in the bedstead frame (10) and supplementary caps (12) finishing off the spring-to-bush assembly.
A bedstead, as the foregoing claim, characterized because the section making up the springs (9) adopts an inverted "U" shape cross section with short vertical arms with a broad horizontal stretch (2). At a point nearly half way up their height, these vertical arms break inwards towards the horizontal strecht, with respective 45° angles, giving the section bevelled (1), longitudinal edges; this section is made from flat, crimped, woven, combed or braided fibres or a combination of them; by subsequent injection onto them in a suitable press-mould of any type of thermostable plastic material such as ortho- and isophthalic polyesters or any other equivalent, either alone or with various organic and inorganic charges such as calcium phthalate, calcium carbonate, talc or others and, during the process, adding tiny amounts of other materials such as fabrics, threads, plastic films with a minimum thickness or paper; proportions of 70% fibre to 30% isophthalic resin or plastic employed are established, as well as the section being obtained with a curvature between 4m and 9m radius, to the effects of obtaining the deflection required in the spring's body.
A bedstead, as claim 2, characterized by having provided for two possible longitudinal projections (3) on the spring's functional surface as a continuation to the bevels (1) of its two short sides. These projections are angular in cross section in the shape of fine grooves and provision is also made for possible longitudinal reinforcing ribs on the inside/underneath part of the section itself.
A bedstead, as claim 1, characterized because the bushes (11), made in plastic, have a slotted body (4) exactly matching the section of the spring whose end they receive and, at their mouth, their side faces and bevelled edges noticeably emerge and are prolonged in thick side lugs (5) located in a plane perpendicular to the body itself in an approximately square shape with their outside vertices curved. This curvature is more marked at their respective upper vertices.
A bedstead, as claim 1, characterized because the supplementary caps (12), also made in plastic, are shaped by a hollow, bottomless body, as a truncated parabola in plan view decreasing in height from the widest part, where it matches the bedstead's frame, to its opposite end, parallel and narrower, in which the height of this supplementary body practically matches that of the springs. At their narrowest end, which faces inwards towards the bedstead's longitudinal centre line, these caps have a mouth coinciding in shape exactly with the section of the springs and, from this mouth, three ribs (6) begin and extend parallel towards the inside of the cap, slightly increasing their height as the cap itself does, acting as a guide and adapting to the shape of the springs which are to be located inside them. The two side ribs, which are the highest and are located on both sides of the spring, are provided on their inside edge with small longitudinal projections (7) emerging towards the centre line of the piece and bevel shaped to hold the springs (9) when pressure is exerted on them when fitted in the bedstead, and it is provided for the said three ribs not to reach the widest final part of the cap in order to leave a clear space between these ribs and the small side pieces (8) which, at this widest end of the cap, close it off and allow it to house and hold the spring receiving bush side lugs (5).
A bedstead, as claim 2, characterized by having elements regulating the springs' elasticity and firmness. Such elements are each made up of a totally rigid piece in a general elongated rectangular prismatic shape providing the special feature of being hollow (13) throughout crosswise, also rectangular in cross section, defining two openings in its two long sides. These openings, as well as the rest of this hollow section, exactly match in size the cross section of the spring (9) to which the regulator is fitted. This latter has two reinforcing thickenings on its shortest ends which, on the outside surface, define concave, knurled arcs (14) for moving them by hand.
A bedstead, as the foregoing claim, characterized because the spring's firmness regulating elements have + and - signs engraved on their topside, which is the most visible, duly aligned in the vicinity of one of their ends and located such that when these regulators are fitted on a bedstead's springs, the + sign appears on the side of the regulator facing the bedstead's centre whilst the - sign is located on the side nearest the bedstead's frame.