Ladder
OwnerGerd Treitzinventor
Life of this patent
Estimating the term…
Abstract
To enable use to be made of relatively thin sheet metal to be employed in the manufacture of a ladder which is formed by punching adjacent openings from the sheet to leave edge strips which are subsequently folded to form stiles and cross pieces which are twisted to form tread bodies, embossed corrugations are incorporated into the twisted metal portions between the tread bodies and the stiles, and stiffening cheeks along the edges of the tread bodies are folded below the said bodies, thereby to impart rigidity to the ladder structure. Additionally or alternatively, holes and/or further corrugations may be provided, and the stiles may, if desired, be of oval cross-section each with connecting cheeks along their facing edges.
Claims11
A ladder comprising a pair of spaced-apart stiles, and a plurality of steps extending between said stiles, said stiles and steps being provided by a one-piece coherent metal sheet divided between the individual said steps, transversely to said stiles to define step bodies which are twisted out of the plane of said metal sheet to form said steps, each said twisted portion having a lesser depth than the step depth, and said stiles being formed by profiling of the flat sheet material, characterised by the provision, in the twisted regions between each said step and said stiles, of formations selected from corrugations and holes, and in that each said step body is stiffened by folding.
Dependencies are inferred from the claim text.