Our Ref: 65501nno P/00/009 Regulation 3.2 AUSTRALIA Patents Act 1990 INNOVATION SPECIFICATION FOR AN INVENTION ENTITLED Invention title: Electric Drill Adapter Sleeve Name of Applicant: Fu-Hsing Lin Address for Service A.P.T. Patent and Trade Mark Attorneys PO Box 222 Mitcham, S.A. 5062 The invention is described in the following statement: ELECTRIC DRILL ADAPTER SLEEVE BACKGROUND OF THE INVENTION (a) Field of the Invention 5 The present invention relates to an electric drill and more particularly to an electric drill adapter sleeve. (b) Description of the Prior Art In construction engineering or plumbing, it is very common to use a power tool. When performing a drilling or locking operation on a working surface like 10 a cement wall, e.g. installing a signboard, putting up an air conditioner or implementing a formwork, a construction worker will need to carry in person an electric drill and a replaceable drill bit and screwdriver bit fitting with the electric drill. Next, in a first stage of construction, the drill bit is installed on a sleeve, and the sleeve is fitted on the electric drill, so that a hole can be drilled on the 15 working surface using the drill bit driven by the electric drill. Then, the drill bit is removed from the sleeve and the screwdriver bit is installed on the sleeve to carry out a second stage of construction. After that, a locking element, such as screw or bolt, is put in the drill hole and the screwdriver bit is abutted at the locking element, so that the electric dill can drive the screwdriver bit to secure 20 the locking element on the working surface, thereby accomplishing the 2 construction operation. However, each time before drilling and locking, the construction worker will always need to carry the drill bit and the screwdriver bit respectively, causing a trouble in carrying and emplacing the bits, as the tools are increased 5 in number. In addition, when drilling and locking, the construction worker will often operate repeatedly between drilling the hole and rotating the locking element; when removing the drill bit from the sleeve, the construction worker has to put the dismantled drill bit in a tool box or pocket, and then searches for the screwdriver bit in the tool box or pocket, followed by installing the 10 screwdriver bit on the sleeve. In this process, a lot of time will be spent, and the drill bit or screwdriver bit can be dropped or lost easily when replacing the bits. Therefore, the operation will be rather inconvenient. SUMMARY OF THE INVENTION Accordingly, the primary object of the present invention is to provide an 15 electric drill adapter sleeve, wherein a ball and a compression spring pass through an opening which is disposed in an annular elastic piece of a concave ring sheathed at a barrel, and then are put into a radial conical hole of the concave ring. Next, the annular elastic piece is rotated by a small angle with respect to the concave ring, allowing a body of the annular elastic piece to be 20 abutted by a distant end of the compression spring away from the ball. 3 Therefore, this electric drill adapter sleeve is not only simple in structure, but convenient in operation and easy to assemble and dismantle. To achieve the abovementioned object, the present invention discloses an electric drill adapter sleeve including a cylinder, a connection piece, a ball, a 5 compression spring and an annular elastic piece, wherein the cylinder is provided with a barrel, a closed end and an open end, with that the closed end and the open end are disposed at each end of the barrel respectively, the open end provides for securing a drilling element removably, the barrel is annularly provided with a concave ring in adjacent to the open end, the concave ring is 10 radially transfixed with a conical hole, and a diameter of the conical hole is gradually enlarged from interior to exterior of the concave ring; the connection piece is extended outward from an axis of the closed end of the cylinder, and is coaxially disposed with the cylinder; the ball is disposed in the conical hole, and is partially exposed out of the concave ring; the compression spring is 15 transfixed in the conical hole, and an end of the compression spring abuts the ball; and the annular elastic piece is sheathed at the concave ring and is provided with a body and an opening, with that the opening of the annular elastic piece is disposed at a predetermined location of the body, providing for the ball and the compression spring to pass through and to be emplaced in the 20 conical hole, followed by rotating the annular elastic piece by a small angle to 4 enable the body of the annular elastic piece to be abutted by the distant end of the compression spring away from the ball. In some embodiments, the open end of the barrel is axially formed with a hexagonal hole to install a drilling element having a hexagonal projection. The 5 drilling element is secured by the compression of the ball and the compression spring. In some embodiments, the connection piece is provided with a hexagonal transversal cross section to connect and secure with an electric drill removably. 10 To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS 15 FIG. 1 shows an exploded schematic view of an electric drill adapter sleeve of the present invention. FIG. 2 shows a three-dimensional schematic view of the electric drill adapter sleeve of the present invention. FIG. 3 shows a partial exploded perspective view of the electric drill adapter 20 sleeve fitting with a drilling element, according to the present invention. 5 FIG. 4 shows an assembly perspective view of FIG. 3. FIG. 5 shows a cutaway schematic view of FIG. 4. FIG. 6 shows a cutaway schematic view of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 5 FIG. 1 shows an exploded schematic view of the electric drill adapter sleeve of the present invention. FIG. 2 shows a three-dimensional schematic view of the electric drill adapter sleeve of the present invention. FIG. 3 shows a partial exploded perspective view of the electric drill adapter sleeve fitting with a drilling element, according to the present invention. FIG. 4 shows an 10 assembly perspective view of FIG. 3. FIG. 5 shows a cutaway schematic view of FIG. 4. FIG. 6 shows a cutaway schematic view of FIG. 3. The electric drill adapter sleeve 100 of the present embodiment comprises a cylinder 1, a connection piece 2, a ball 3, a compression spring 4 and an annular elastic piece 5. 15 Referring to FIG.1 to FIG.6, the cylinder 1 is provided with a barrel 11, a closed end 12 and an open end 13. The closed end 12 and the open end 13 are disposed at each end of the barrel 11 respectively. The open end 13 provides for a drilling element 6 to be secured removably. The barrel 11 is annularly provided with a concave ring 14 in adjacent to the open end 13. The 20 concave ring 14 is radially transfixed with a conical hole 15, and a diameter of 6 the conical hole 15 is enlarged from interior to exterior of the concave ring 14. Moreover, the open end 13 of the barrel 11 is axially formed with a hexagonal hole 16 to install a drilling element 6 having a hexagonal projection 61. The drilling element 6 is secured by the compression of the ball 3 and the 5 compression spring 4. The connection piece 2 is extended outward from an axis of the closed end 12 of the cylinder 1 and is coaxially disposed with the cylinder 1. The connection piece 2 is provided with a hexagonal transversal cross section, meaning that the connection piece 2 can be, but not limited to, a hexagonal 10 revolving rod. The connection piece 2 having the hexagonal transversal cross section can be connected and secured with an electric drill (not shown in the drawings) removably. The ball 3 can be installed in the conical hole 15, and is partially exposed out of the concave ring 14. 15 The compression spring 4 can be transfixed in the conical hole 15 and an end of the compression spring 4 abuts the ball 3. The annular elastic piece 5 is sheathed at the concave ring 14 and is provided with a body 51 and an opening 52. The opening 52 of the annular elastic piece 5 is disposed at a predetermined location of the body 51, allowing 20 the ball 3 and the compression spring 4 to pass through and to be emplaced in 7 the conical hole 15. After emplacing the ball 3 and the compression spring 4 in the conical hole 15, the annular elastic piece 5 is rotated by a small angle with respect to the concave ring 14, enabling the body 51 of the annular elastic piece 5 to be 5 abutted by a distant end of the compression spring 4 away from the ball 3. By the abovementioned structures, the present invention is simple in structure and operates conveniently. In addition, the present invention can be assembled and dismantled easily. It is to be understood that the above description and drawings are only 10 used for illustrating some embodiments of the present invention, not intended to limit the scope thereof. Any variation and deviation from the above description and drawings should be included in the scope of the present invention. 15 20 8