Center-foldable seat back, seat with the same, and method of manufacturing center-foldable seat back

A method of manufacturing a center-foldable seat back in which a seat back upper part tilts forward relative to a seat back lower part, comprising:

• in a seat back upper part covering step:
• assembling an upper pad to an upper frame;
• putting an upper cover of a trim cover on the upper pad;
• reversingly rolling up a lower cover of the trim cover up from an open side that is not sewn with the upper cover to hold a connecting member in an open state, the connecting member being provided at a portion between the upper cover and the lower cover of the trim cover and being openable and closeable;
• and
• inserting all of the upper frame to which the upper pad is assembled into the upper cover;
• holding, in a tilting step, the upper frame in a tilted state by being tilted relative to the lower frame;
• the method further comprising, subsequent to the above steps:
• closing, in a closing step, the connecting member of the trim cover to close the upper cover;
• and
• disposing, in a seat back lower part covering step, after the closing step, all of the lower frame to which a lower pad is assembled on an inside of the lower cover and then closing the open side.

A method of manufacturing a center-foldable seat back in which a seat back upper part tilts forward relative to a seat back lower part, comprising:

• producing, in a back frame producing step, a back frame, which has an upper frame supporting the seat back upper part and a lower frame supporting the seat back lower part so that the upper frame is tiltably connected to the lower frame;
• in a trim cover producing step:
• sewing together an upper cover of the trim cover and a lower cover of the trim cover along an entire periphery at a mutual contact position;
• disposing a first connecting part at a sewing position of a front cover;
• and
• disposing a second connecting part at a sewing position of a rear cover, thereby producing the trim cover to which a connecting member is attached;
• holding, in a tilting step, the upper frame produced in the back frame producing step in a tilted state by being tilted relative to the lower frame;
• in a seat back upper part covering step:
• assembling an upper pad to the upper frame while the upper frame is held in a state of being tilted in the tilting step;
• putting the upper cover of the trim cover on the upper pad;
• then, reversingly rolling up the lower cover of the trim cover from an open side that is not sewn with the upper cover;
• holding the connecting member of the trim cover in an open state;
• and
• thereafter, inserting all of the upper frame to which the upper pad is assembled into the upper cover;
• closing, in a closing step, the connecting member of the trim cover to close the upper cover;
• and
• after the closing step, in a seat back lower part covering step:
• assembling a lower pad to the lower frame;
• rolling down the lower cover of the trim cover;
• and
• disposing all of the lower frame to which the lower pad is assembled on the inside of the lower cover, and then closing the open side.