Prefabricated spiral staircase

Abstract

The present invention relates to a prefabricated spiral staircase in which the heights between treads can be freely and finely adjusted, thus being conveniently assembled and installed at installation sites having different story heights.

1 . A prefabricated spiral staircase, comprising:
 a base configured to be fastened to a floor;   a center pole configured such that a lower end thereof is installed on the base;   a plurality of spacers configured to be inserted over the center pole;   treads each configured such that one side thereof is inserted over the center pole between corresponding adjacent two of the spacers;   outside stringers each disposed on an opposite side of the tread; and   coupling members each configured to couple the opposite side of the tread to the outside stringer;   wherein each of the spacers comprises a cylindrical pipe, and a lower or upper cap configured to be inserted over a lower or upper side of the cylindrical pipe; and   wherein one or more height adjustment disks are further disposed internally between the lower cap and a lower end of the cylindrical pipe or between the upper cap and an upper end of the cylindrical pipe.   
     
     
         2 . The prefabricated spiral staircase of  claim 1  wherein the center pole is a male threaded pole, and nuts are each engaged with the center pole so that the lower cap applies pressure to the one side of the tread. 
     
     
         3 . The prefabricated spiral staircase of  claim 1  wherein the outside stringers are configured such that at least a plurality of linear side plates is assembled together and form a rectangular shape when viewed in a plan view. 
     
     
         4 . The prefabricated spiral staircase of  claim 3  wherein each of the coupling members comprises: a bracket configured to be disposed in a recession formed by cutting out a portion of the opposite side of the tread; first fastening metal elements configured to insert and fasten the bracket into the opposite side of the tread; and second fastening metal elements configured to insert and fasten the bracket into an inner surface of a corresponding one of the linear side plates. 
     
     
         5 . The prefabricated spiral staircase of  claim 4  wherein each of the brackets comprises: a bracket body configured to have an outer surface adapted to come into contact with the inner surface of the linear side plate and an inner surface adapted to come into contact with a side surface of the tread; first through holes configured to penetrate through the inner and outer surfaces of the bracket body, and to be supported by the first fastening metal elements; and second through holes configured to penetrate through a top surface of the bracket body and the outer surface of the bracket body or through a bottom surface of the bracket body and the outer surface of the bracket body, and to be supported by the second fastening metal elements. 
     
     
         6 . A spacer coupling structure for a prefabricated spiral staircase, comprising:
 a center pole configured to be fastened to a floor;   a plurality of spacers configured to be inserted over the center pole; and   treads each configured such that one side thereof is inserted over the center pole between corresponding adjacent two of the spacers;   wherein each of the spacers comprises a cylindrical pipe, and a lower or upper cap configured to be inserted over a lower or upper side of the cylindrical pipe; and   wherein one or more height adjustment disks are further disposed internally between the lower cap and a lower end of the cylindrical pipe or between the upper cap and an upper end of the cylindrical pipe.   
     
     
         7 . The prefabricated spiral staircase of  claim 2  wherein the outside stringers are configured such that at least a plurality of linear side plates is assembled together and form a rectangular shape when viewed in a plan view. 
     
     
         8 . The prefabricated spiral staircase of  claim 7  wherein each of the coupling members comprises: a bracket configured to be disposed in a recession formed by cutting out a portion of the opposite side of the tread; first fastening metal elements configured to insert and fasten the bracket into the opposite side of the tread; and second fastening metal elements configured to insert and fasten the bracket into an inner surface of a corresponding one of the linear side plates. 
     
     
         9 . The prefabricated spiral staircase of  claim 8  wherein each of the brackets comprises: a bracket body configured to have an outer surface adapted to come into contact with the inner surface of the linear side plate and an inner surface adapted to come into contact with a side surface of the tread; first through holes configured to penetrate through the inner and outer surfaces of the bracket body, and to be supported by the first fastening metal elements; and second through holes configured to penetrate through a top surface of the bracket body and the outer surface of the bracket body or through a bottom surface of the bracket body and the outer surface of the bracket body, and to be supported by the second fastening metal elements.