Lock apparatus

A U-lock apparatus, comprising a lock body and a shackle, the shackle comprising a primary structure, the primary structure comprising two engaging heads inserted into the lock body for being engagingly locked and a link segment which is located between the two engaging heads and exposed out of the lock body, the link segment having at least one arcuate bent section, wherein a diamond layer is applied to a surface of the link segment, a thickness B of the diamond layer being greater than or equal to 0.2 mm, a center radius R of the arcuate bent section being greater than or equal to 15 mm, a central angle of the arcuate bent section being in a range from 30° to 150°, the thickness B of the diamond layer is in a range from 0.3 mm to 0.6 mm;

• the link segment comprises a first straight section and a second straight section, the two engaging heads being located at end portions of the first straight section and the second straight section, respectively, the first straight section and the second straight section being parallel disposed with a center distance S ranging from 60 mm to 150 mm;
• the center radius R of the arcuate bent section is greater than or equal to a diameter D of the link segment;
• and the link segment further comprises the third straight section and a fourth straight section, two ends of the third straight section being connected to the first straight section and the fourth straight section via the arcuate bent sections, respectively, two ends of the fourth straight section being connected to the second straight section and the third straight section via the arcuate bent sections, respectively.