Spherical bearing and plastic block with spherical surface for the same

A spherical bearing installed between an upper structure and a lower structure and supporting the upper structure on the lower structure, the spherical bearing comprising:

• a plastic spherical block made of plastic and including a convex spherical surface bulging upward or downward;
• a spherical groove member including a spherical groove with which the convex spherical surface engages and surface-contacts and allowing rotation with respect to the plastic spherical block;
• and
• a weight-delivering member installed opposite to the spherical groove member with the plastic spherical block in the middle and delivering a weight of the upper structure to the plastic spherical block or receiving the weight of the upper structure from the plastic spherical block and then delivering to the lower structure,
• wherein a frictional surface of the plastic spherical block rubbing against the spherical groove member or the weight-delivering member is made of an engineering plastic having a hardness of 75 D through 95 D, and
• wherein the engineering plastic includes one selected from the group consisting of polyamide (PA), polyacetal or polyoxymethylene (POM), polyethylene terephthalate (PET), polysulfone resin (PSU), polyether sulfone (PES), polyphenylene sulphide (PPS), polyphenylene sulfone (PPSU), polyether imide (PEI), polyamide imide (PAI), polybenzimidazole (PBI), polyimide (PI), and polyether ether ketone (PEEK),
• wherein the plastic spherical block includes a core material made of metal and an engineering plastic layer enclosing the core material.