The invention relates to a panel for a walking surface, comprising a core plate which is received between two cover layers of a first plastic material, the core plate being provided with respective longitudinal profiles along two first parallel opposite edges.

Known are elongate panels for a walking surface, for instance for a construction scaffold, a dismantlable stage or a dismantlable stand. Such panels are for instance assembled from a multi-ply board provided on its long sides with respective longitudinal profiles of aluminium or galvanized steel, which longitudinal profiles are connected by aluminium or galvanized steel transverse profiles which are provided on their side remote from the panel with hooks for the purpose of enabling clamping of the panel part between two scaffold tubes or into a stage frame.

Panels with a multi-ply board and steel longitudinal and transverse profiles are relatively heavy, this being deemed a drawback in the application as scaffold or stage panels since the panels have to be transported, arranged and removed again relatively often, this requiring a great deal of heavy manual labour. Panels with longitudinal and transverse profiles of aluminium are somewhat lighter, but have the drawback of being relatively expensive.

Panels with a lower weight have recently been proposed, wherein the multi-ply board is replaced by a sandwich panel, wherein a light plastic plate is received between two cover layers of a fibre-reinforced plastic material, and the whole is enclosed by a framework of aluminium. The production of such panels is relatively labour-intensive, so that these panels have the drawback that they can only be produced at an inherently high cost price.

It is an object of the invention to provide a panel for a walking surface which is light in weight, has a high load- bearing capacity, is durable and can be produced at an acceptable cost.

These objects are achieved, and other advantages gained, with a panel of the type stated in the preamble, wherein according to the invention the longitudinal profiles are manufactured from a second plastic material and formed continuously on the core plate and the cover layers.

The continuous forming of the longitudinal profiles on the cover layers provides the advantage that an exceptionally strong and stiff panel is created which, due to the use of a second plastic material for the longitudinal profiles, is light and durable and can moreover be produced in very efficient manner.

In an embodiment of a panel according to the invention the first plastic material is a glass fibre-reinforced polyester.

The second plastic material is for instance a glass fibre-reinforced polyester.

In a practical advantageous embodiment the longitudinal profiles each enclose in a cross-section at least one cavity. A cavity in the longitudinal profiles can be utilized for the purpose of receiving necessary coupling elements therein, while hollow longitudinal profiles are of course also relatively light in weight.

In an embodiment the core plate in a panel according to the invention is manufactured from a third plastic material, preferably a polypropylene.

In another embodiment the core plate has a honeycomb structure.

A honeycomb structure provides the advantage of a relatively low weight in combination with a great stiffness.

In a subsequent embodiment the core plate is provided with respective transverse profiles along two second parallel opposite edges.

These transverse profiles are for instance coupled at their outer ends to the two longitudinal profiles, and are provided for instance with hooks which are directed in the longitudinal direction of the panel and which can be hooked round the tubes of a scaffold or stage in order to thus suspend the panel in this scaffold or this stage.

In a practical advantageous embodiment, wherein the longitudinal profiles each enclose in a cross-section at least one cavity and the core plate is provided with respective transverse profiles along two second parallel opposite edges, the transverse profiles are provided with coupling elements co-acting with the respective cavities for coupling the transverse profiles to the longitudinal profiles.

The invention also relates to a method for manufacturing a panel of the type stated in the preamble, the method being characterized by the steps of

(i) providing a plate, the length of which is at least equal to the length of the core plate and the width and thickness of which correspond to the width and thickness of the core plate,

(ii) providing two first foils of a first extrudable plastic material wound onto respective first rolls, (iϋ) providing two second foils of a second extrudable plastic material wound onto respective second rolls,

{iv) simultaneously unwinding the respective first and second foils from the respective first and second rolls and feeding the first and second foils and the plate into a pultrusion machine adapted for this purpose,

(v) extruding with the pultrusion machine a semimanufactured product comprising a plate received between cover layers of the first material and having longitudinal profiles of the second material formed thereon, and (vi) separating a part of the semi-manufactured product formed in step (v) and selected for this purpose as panel.

The invention will be elucidated hereinbelow on the basis of an exemplary embodiment with reference to the drawings . In the drawings

Fig. 1 is a perspective top view of a first embodiment of a panel according to the invention, Fig. 2 is a perspective top view of a detail of the panel shown in fig. 1, and

Fig. 3 is a perspective top view of a highly simplified representation of the production process using a pultrusion machine for making a semi-manufactured product of the panel shown in fig. 1.

Corresponding components are designated in the figures with the same reference numerals.

Fig. 1 shows a rectangular scaffold panel 10 assembled from a sandwich structure 1 (shown in fig. 3) of a polypropylene plate 2 (shown in fig. 3) with a honeycomb structure which is received between an upper cover layer 3 and a lower cover layer 4 (shown in fig. 3} of a glass fibre- reinforced polyester. Hollow longitudinal profiles 5, likewise of a glass fibre-reinforced polyester, are formed continuously along the edges on the long sides of the plate. Arranged along the short sides of the plate are aluminium transverse profiles 6 which are provided with hooks 7 with which panel 10 can be hooked into the frame of a scaffold or stage.

Fig. 2 shows a detail of panel 10 of fig. 1, with a part of a transverse profile 6 which is provided at its outer ends with protrusions 8 which protrude into respective cavities 9 of the longitudinal profiles and are fixed therein using bolts 11. The figure also shows studs 12 on upper cover layer 3. These studs 12 can for instance be made from longitudinal ribs which are obtained by means of a pultrusion process and from which portions are cut away.

Fig. 3 shows schematically a pultrusion machine 13 having on the infeed side (on the left in the figure) a polypropylene plate 2 with a honeycomb structure with a length which is at least equal to the length of the core plate to be produced, and the width and thickness of which correspond to the width and thickness of the core plate. Disposed above and below plate 2 are two horizontal rolls 14, 15 with a glass fibre-reinforced polyester foil, and on the left and right of plate 2 (as seen in throughfeed direction, indicated with arrow 18} are disposed two vertical rolls 16, 17 with a glass fibre-reinforced polyester foil. Machine 13 is provided with means for heating and subsequently forming the plastic foils to be fed in from rolls 14, 15, 16, 17, wherein the upper and lower cover layers 3, 4 are formed from the foil material of horizontal rolls 14, 15, and longitudinal profiles 5 are formed from the foil material from vertical rolls 16, 17. Obtained on the outfeed side of machine 13 (on the right in the figure) is a semi- manufactured product 1 comprising a plate 2 which is received between cover layers 3, 4 and has longitudinal profiles 5 formed thereon, and from which a part suitable for a panel can be separated by means of sawing, cutting or other process, which part can if desired be further processed, for instance to impart a rougher surface structure to upper cover layer 3. By mounting transverse profiles on the separated part, this part is suitable for use as for instance scaffold panel or stage panel or stand panel.