Sofa seat frame, sofa base assembly, sofa and sofa production and assembly process

A sofa seat frame, characterized by comprising two cross beams (12) arranged at intervals and two longitudinal beams (11) connecting the two cross beams (12), wherein:

• a plurality of supporting elastic pieces (13) are arranged between the two cross beams (12);
• and
• each longitudinal beam (11) comprises a first supporting plate (111) for supporting a seat cushion and a first side plate (112) arranged at one side of a lower part of the first supporting plate (111) and used for being detachably connected with a sofa fabric on the seat cushion;
• each longitudinal beam (11) is a metal piece and comprises a second side plate (113) arranged at a distance from the first side plate (112) and located on an other side of the lower part of the first supporting plate (111), and the first supporting plate (111) connecting the first side plate (112) with the second side plate (113) from a top of the first side plate (112) and a top of the second side plate (113);
• further comprising a first connecting piece (14) for being connected with a sofa rack, the first connecting piece (14) comprising two fifth side plates (142) arranged at intervals and a third supporting plate (141) connecting bottoms of the two fifth side plates (142), wherein:
• the third supporting plate (141) is connected with the sofa rack;
• and
• one fifth side plate (142) is connected to the first side plate (112) of the longitudinal beam (11), and another fifth side plate (142) is connected to the second side plate (113) of the longitudinal beam (11).