Cap structure having an inner surface concave feature and zipper head assembly structure using the same

A zipper head assembly structure, comprising:

• a sliding member having a first retaining seat and a second retaining seat, wherein the first retaining seat has a hook groove, and the second retaining seat has a hook hole;
• a pull tab having an end portion disposed between the first retaining seat and the second retaining seat;
• a locking hook disposed on the sliding member, wherein the locking hook has a first end portion disposed inside the hook groove and a second end portion passing through the hook hole;
• a cap body having two opposite end portions respectively disposed on the first retaining seat and the second retaining seat, wherein the cap body has at least two first retaining blocks corresponding to each other and at least two first outer concave grooves corresponding to each other and respectively adjacent to the at least two first retaining blocks, wherein the cap body has an inner surface, an outer surface and a bottom surface connected between the inner surface and the outer surface, and the at least two first outer concave grooves are disposed on the outer surface of the cap body;
• and
• an elastic piece disposed between the inner surface of the cap body and the locking hook and abutted against the locking hook, wherein the at least two first retaining blocks contact the elastic piece for retaining the elastic piece;
• wherein the cap body has at least two first inner concave grooves corresponding to each other, the at least two first retaining blocks are respectively and outwardly extended from the at least two first inner concave grooves, and the at least two first inner concave grooves are disposed on the inner surface of the cap body;
• wherein each first inner concave groove has a first end connected to the bottom surface of the cap body and a second end opposite to the first end and far away from the bottom surface of the cap body, and a width of the first inner concave groove is narrowed gradually from the first end to the second end of the first inner concave groove.

A cap structure having an inner surface concave feature, comprising:

• a cap body having at least two first retaining blocks corresponding to each other and at least two first outer concave grooves corresponding to each other and respectively adjacent to the at least two first retaining blocks, wherein the cap body has an inner surface, an outer surface and a bottom surface connected between the inner surface and the outer surface, and the at least two first outer concave grooves are disposed on the outer surface of the cap body;
• and
• an elastic piece disposed on the inner surface of the cap body, wherein the at least two first retaining blocks contact the elastic piece for retaining the elastic piece;
• wherein the cap body has at least two first inner concave grooves corresponding to each other, the at least two first inner concave grooves are disposed on the inner surface of the cap body, and a width of each first inner concave groove is narrowed gradually.