Pool Section 29 Regulation 3.2(2)) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Screws The following statement is a full description of this invention, including the best method of performing it known to us: SCREW BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a screw, more particularly 5 to a rapid tapping screw with less torque. 2. Description of the Related Art In accordance with the conventional screw, as shown in Fig. 1, it includes a head.11 and a shank 12 connecting with the head 11; wherein, there are several helical threads 10 13 built upon the surface of said shank 12. When the conventional screw 1 is screwed in a wooden object 2, along with the shank 12 screwing in, by means of the shearing action of the threads 13, it is fastened in there. However, due to the facts that the threads 13 15 cannot cut through the wooden fabric, the wooden fabric chips produced could not be removed out rapidly, and so on, the tapping resistance is increased. Hence, the worker has to apply bigger tapping force on it in order to implant the screw 1 into the object 2, even if the greater tapping 20 torque applied occurs the screw 1 overloading to be broken up. Therefore, the conventional screw 1 should be improved in design. For this sake, there are some manufactures innovating the conventional screw 1. An innovated screw 3, as shown 25 in Fig. 2, is came out, which is comprised of a head 31 and a shank 32 connecting with said head 31, and a thread 33 helically built upon the shank 32, wherein on the thread 33 there is even number of axial slots 331 formed. Referring to Fig. 3, when fasten the screw 3, take the advantages of the axial slots 331 of saidthread33 to increase the containing space of the wooden fabric chips. Meanwhile, 5 cooperating to the cutting process of said thread 33, the side edges of the axial slots 331 is designed to work as cutting rims for getting rapid tapping with less force goal. However, in practice, there are some shortcomings existing in the screw 3 as followings: 10 1.Not getting desired fastening effect: When tap into the object 4, 'due to that the small tooth height of the thread 33 projected up from the shank 32, the cutting effect could not get desired level in cutting and holding chips even though the thread 33 is cut cross 15 with the axial slots 331. Therefore, the actual practice effect of the screw 3 has not been improved obviously comparing with the conventional screw 1. 2.Tapping resistance still big: As previously discussed, cutting said axial slots 20 331 naturally form a vertical side 332 crossing the thread 33. Therefore, when tap the thread 33 in, the vertical side 332 directly strikes and cuts the flexible object 4. Thus the elastic wooden fabric cannot be cut through~ immediately. On the contrary, the wooden fabric twins on 25 the axial slot 332 and the shank 32, further to increase the tapping resistance of the screw 3.
3 SUMMARY OF THE INVENTION It is, therefore, a main object of the present invention to provide a rapid tapping screw with lower tapping torque. 5 With this in mind, the present invention provides a screw comprising a head 51, a shank 52 extending from the head , and a helical thread 53 formed on the outside of the shank, wherein, said thread has an even number of axial slots 534 thereby forming thread portions, each thread portion having an upper flank 531, a lower flank 532, an edge 533 on a joint line between the upper and low 10 flanks, and a shear section 535 , wherein each shear section is beveled with an angle that is non-perpendicular with respect to a direction of rotation of the screw during insertion of the screw into a material thereby forming a cutting edge 536 on a joint line between the shear section 535 and the lower flight 532. 15 BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing is to provide a further understanding of the invention and to incorporate in and constitute a part of this specification. The drawing illustrates an embodiment of the invention, and together with the description, serves to explain the principles of the invention. In the drawing, 20 Fig. 1 is a sectional view of the prior art. Fig. 2 is a schematic view of the second prior art. Fig. 3 is a cross-section view showing the implanted stated of the second prior art. 25 Fig. 4 is a schematic view of the present invention. Fig. 5 is a enlarged view of Fig 4 A part showing the thread of the present invention.
4 Fig. 6 is a cross-section view showing the implanted stated of the present invention. 5 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 4 and Fig. 5, the first embodiment of the present invention provides a screw 5 consisted of a head 51, a shank 52 under the head 51 in a whole body, and a thread 53 helically built upon the outside trunk of the shank 52. Wherein, the shank 52 has a base circle surface 521 surrounding the axis. The 10 helical thread 53 projects from the base circle surface 521. The thread 53 is consisted of an upper flank 531, a lower flank 532, and a edge 533 on the joint line of the upper and lower flanks 531 532, and an even number of axial slots 534 formed on the thread 53 of the shank 52 in equidistance. The feature is that each axial slot 534 is beveled with a back angle to form a shear section 535 from the 15 upper flank 531 to the low flight 532, so as to form a cutting edge 536. Referring to Fig. 5 and Fig. 6, when secure the screw 5 on an object 6, the worker should vertically press the screw 5 on the surface of the object 6 with the bottom end, and continuously exert tapping forcing on the head 51 of the screw 5. 20 Hence the thread 53 is turned simultaneously, in order to tap into the object 6. Along with the implanting of the thread 53, the edge 533 of the thread 53 can cut the object 6, and the cutting edges 536 consist of the shear section 535 and the lower flanks 532 can also cut simultaneously. So that, when screwing in the thread 53, the cutting edges 536 can circularly cut for rapid and efficient shearing 25 of, for example, wood material, further to reduce the tapping resistance to get rapid fastening effect and to reduce the tapping torque. It is for sure that the uncut wood material by the cutting edges 536 can be led by the shear section 535 to the rear cutting edge for cutting through.
5 In accordance with above description, the improvement of the present invention based on the prior art can be obviously found as following: 5 1. Better fastening effect: when screw into the object 6 with the screw 5, due to the shear section 535 at the side of the axial slot 534 beveled on the thread 53, the size of the axial slot 534 is expended to increase the space of containing chips for facilitating to cut fluently. 10 2. Rapid fastening with smaller tapping torque: as above description, the shear section 535 beveled on the thread 53 at the side of the axial slot 534 cooperates to the lower flank 532 to form a sharp cutting edge 536. Thus, as fastening the thread 53, not only utilises 15 the original edge 533 to cut, but also the cutting edge 536 is to shear the wood material firstly to efficiently cut the wood material fabric. It is sure that the uncut wood material by the cutting edge 536 can be led by the shear section 535 to the rear cutting edge for cutting through. Therefore it is helpful to reduce tapping torque when 20 screwing in the screw 5 thereby preventing the screw 5 from breaking up. According to the above description, the main feature of the present invention is to bevel a shear section on the thread at the side of the axial slot, 25 and the shear section cooperates with the lower flank to form a cutting edge to help the thread do rapid cutting to screw in the object. Meanwhile, during the screw tapping in process, the chips produced can be also removed and contained immediately. To get rapid fastening with smaller tapping torque. 30 While the present invention has been described in connection with what is considered the most practical and preferred embodiments. It is understood that this invention is not limited to the disclosed embodiments but is intended to cover 6 various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements. 5