Ball retainer chain, a method of making the same, and a linear guide apparatus

A ball retainer chain comprising a flat belt and a plurality of spacers;

• wherein, said flat belt including holes that are axially arranged and separating portions each disposed between every two of said holes;
• said spacers combining to said separating portions;
• an hole surface on said hole being formed between said flat belt along a vertical direction and two spacers;
• each separating portion of said flat belt having an upper surface and a lower surface, and said upper surface and said lower surface respectively including a left side and a right side;
• said spacer being further divided into an upper spacer and a lower spacer that individually combine to said upper surface and said lower surface of said separating portion of said flat belt;
• surfaces between said upper/lower spacers and said holes being formed by a smooth surface, a part of which being formed by a spherical surface and smoothly connected to said hole surface on said flat belt, allowing a connection between said holes and said spherical surfaces thereof to form an upper enveloping surface and a lower enveloping surface, respectively;
• said spherical surfaces including an opening, the other part of a smooth surface being arranged as an outward-stretched curve along a tangent line of said opening of said spherical surface;
• an opening direction of either said upper or said lower enveloping surface being slantingly disposed between a vertical direction of the cross-section of the flat belt and a horizontal direction of the cross-section of the flat belt of said flat belt;
• said spherical surfaces of said upper spacer and said lower spacer being interlacedly disposed at a left side and a right side, respectively;
• said opening directions being defined oppositely.