Abstract: The invention provides an expansion screw set, a hollow nail and an interior nail. The expansion screw set is composed of the hollow nail and the interior nail. The hollow nail has a hollow structure. A first thread and a second thread are provided for the inside and the outside of the hollow nail. The interior nail has a third thread. The hollow nail could nail an object through the first thread. The third thread of the interior nail corresponds to the second thread of the hollow nail. Therefore, the interior nail can be fastened into the hollow structure after the interior nail is nailed into the hollow nail. Moreover, the hollow nail has a separation line which runs parallel to the penetration direction of the hollow structure. Alternatively, the hollow nail has a plurality of penetration holes which is vertical to the penetration direction of the hollow structure. After the interior nail is nailed into the hollow structure, the separation line can be stretched out through the interior nail.

Abstract: The invention provides an expansion screw set, a hollow nail and an interior nail. The expansion screw set is composed of the hollow nail and the interior nail. The hollow nail has a hollow structure. A first thread and a second thread are provided for the inside and the outside of the hollow nail. The interior nail has a third thread. The hollow nail could nail an object through the first thread. The third thread of the interior nail corresponds to the second thread of the hollow nail. Therefore, the interior nail can be fastened into the hollow structure after the interior nail is nailed into the hollow nail. Moreover, the hollow nail has a separation line which runs parallel to the penetration direction of the hollow structure. Alternatively, the hollow nail has a plurality of penetration holes which is vertical to the penetration direction of the hollow structure. After the interior nail is nailed into the hollow structure, the separation line can be stretched out through the interior nail.