Concave square tube lifting storage shelf

A concave square tube lifting storage shelf, comprising:

• a plurality of post components, each comprising a concave square tube, each concave square tube comprising a first plate, a second plate parallel to the first plate, a third plate, and a concave plate, wherein each concave square tube includes two sides of the third plate respectively connected to the first plate and the second plate, two sides of the concave plate are respectively connected to the first plate and the second plate, and a hollow portion provided within;
• two fixed storage layers, each comprising a fixed shelf and four first assembly components, wherein the four first assembly components are respectively provided at four corners of the corresponding fixed shelf, the four first assembly components are respectively fitted onto an outer side of the corresponding concave square tube, and the two fixed storage layers are respectively assembled between the post components through the corresponding four first assembly components;
• and
• a plurality of movable storage layers, located between the two fixed storage layers, wherein each of the movable storage layers comprises a movable shelf and four second assembly components, the four second assembly components are respectively provided at four corners of the corresponding movable shelf, wherein a size of the four second assembly components is larger than a size of the concave square tubes, and the movable storage layers can move between the two fixed storage layers along a lifting direction, and the movable storage layers are respectively assembled between the post components through the four second assembly components;
• wherein each of the plurality of post components comprise an elongated fastener provided on its concave square tube, each first assembly component comprising at least one convex groove and at least one opening, each convex groove connected with a corresponding opening, each elongated fastener fastened to a corresponding opening, and each convex groove holding a top of a corresponding elongated fastener.