Fire escape – ladder – or scaffold – Platform
Patent
1994-12-02
1995-08-22
Chin-Shue, Alvin C.
Fire escape, ladder, or scaffold
Platform
182119, E04G 115
Patent
active
054431379
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to a method for making a scaffold board for a building scaffold wherein a substantially smooth and continuous upper sheet section which forms the upper side of the scaffold board is connected to a waved lower sheet section which has wave bottoms and wave tops of a trapezoidal cross-section and forms the bottom side of the scaffold board and the cavity formed between the upper and lower sheet sections is subsequently foamed with a foam which expands during curing.
Such a scaffold board is e.g. known from French application 24 57 946. In this application, however, the scaffold board consists of an upper continuous plank and a lower continuous plank, with a sheet waved in the form of a trapezoid being provided as a core between the two planks.
In comparison with conventional scaffold boards that consist of thick wooden boards, the above-mentioned scaffold boards have the advantage that they are relatively weatherproof. The use of steel sheets, however, increases the weight of scaffold boards in cases where an adequate stiffness of the boards is desired.
It is therefore the object of the present invention to improve a scaffold board of the above-mentioned kind in such a way that its stability is increased while its weight is reduced at the same time.
This object is attained according to the invention by connecting the lower sheet section substantially pointwise to the upper sheet section on the wave tops of the lower sheet section, which face the upper sheet section, and by subsequently foaming which is formed between the upper and lower sheet sections using a foam that expands during curing and squeezes the sheet sections apart.
The stiffness of the scaffold board is considerably increased by this squeezing apart of the upper sheet section relative to the lower, sheet section. It is here worth mentioning that the sheet thickness of the sheet sections can be kept very small for static reasons. A certain minimum thickness is only required for the upper sheet section to prevent the sheet section from being damaged by falling tools. The linear connection of the upper and lower sheet sections which is substantially pointwise or sectionwise has the effect that the foam filled into the cavity deforms at least slightly during its expansion and squeezes the sections apart. Even in cases where the connection of the wave tops of the lower sheet section to the upper sheet section permits some kind of movement, such movements are prevented by the foam which squeezes the two sheet sections apart. The scaffold board is entirely stiff for a person stepping on the board, i.e. evenly stiff over the entire surface of the scaffold board.
Although a foamed scaffold board is already known from GB 20 58 188, the upper side and the lower side of the scaffold board consist of glass fiber-reinforced plastics and the cavities thereof are merely filled. A squeezing apart of the upper side of the scaffold board and the bottom side is neither intended nor desired because the glass fiber-reinforced plastics would be damaged thereby.
In a preferred embodiment the foam may be polyurethane foam.
The cavity which is enclosed by the upper and lower sheet sections can be implemented in a simple way by bending the upper sheet section downwards along its longitudinal edges and by the upper sheet section surrounding the longitudinal edges of the lower sheet section. This has the advantage that the longitudinal edges need not be connected to each other in a special way. Rather, the foam expanding in the cavity presses into each other the longitudinal edges that encompass each other. In a preferred embodiment the longitudinal edges of the lower sheet section are formed by wave bottoms spaced apart from the upper sheet section, the wave bottoms have formed therein, adjacent to the longitudinal edges, longitudinally extending and upwardly directed beads which are engaged from below by a hook-shaped engaging portion of the upper sheet section. This results in a positive locking of the longitudinal edges of the upper a
REFERENCES:
patent: 4644724 (1987-02-01), Schijf
Chin-Shue Alvin C.
Josef Welser oHG Profilier- und Stanzwerk
MacPherson Alan H.
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