Abstract: The present invention pertains to a bimate screw providing with a first section alternating with a second threaded section; wherein, the second threaded section has a smaller outer diameter than the first threaded section, and further a plurality of concavities are disposed on each thread of the second threaded section for defining two flanks therein. In this manner, both the first and the second threaded sections facilitate to sever and shatter cuttings so as to reduce the screwing resistance and prevent the object from being damaged under the accumulation of cuttings; simultaneously, the bimate screw effectively attains to a good resistance of extraction from the object by the concavities receiving the remaining cuttings which are not guided out of the object.

Abstract: A screw with low drilling resistance comprises a head portion, a shank portion, a plurality of first threads, a drilling portion, and a plurality of second threads. Wherein, a plurality of opening slots are correspondingly defined on the second threads, and a first included angle of the first threads is smaller than a second included angle of the second threads. Thereby, the opening slots on the second threads efficiently provide the first threads with an auxiliary cutting effect and preferably offers a debris accommodating room. The first threads including the smaller first included angle favorably reinforce the bearing force of the second threads including the larger second included angle, thereby promoting the cutting effect of the screw and allowing a speedy screwing.

Abstract: A screw with low drilling resistance comprises a head portion, a shank portion, a plurality of first threads, a drilling portion, and a plurality of second threads. Wherein, a plurality of opening slots are correspondingly defined on the second threads, and a first included angle of the first threads is smaller than a second included angle of the second threads. Thereby, the opening slots on the second threads efficiently provide the first threads with an auxiliary cutting effect and preferably offers a debris accommodating room. The first threads including the smaller first included angle favorably reinforce the bearing force of the second threads including the larger second included angle, thereby promoting the cutting effect of the screw and allowing a speedy screwing.

Abstract: A self-drilling screw is in particular to a drill portion having a non-threaded first drilling section connecting with the shank and a second drilling section connecting with said first drilling section and forms two grooves therein. Moreover, the whole first drilling section is formed as an oval-shaped pillar and it has two ridges extending therefrom. Furthermore, the diameter of the first drilling section is smaller than the diameter of the second drilling section, and the length of the second drilling section is between the length of one-third drill portion and the length of two-thirds drill portion. Therefore, due to the aforesaid features and the two drilling sections, the molds for manufacturing the screws suffer less damage while in operation and the manufacturing cost is therefore reduced. The present invention is also good at increasing the screwing speed. Moreover, the surface of the first drilling section also has the function of allowing the user to engrave a mark thereon.

Abstract: The present invention pertains to a bimate screw providing with a first section alternating with a second threaded section; wherein, the second threaded section has a smaller outer diameter than the first threaded section, and further a plurality of concavities are disposed on each thread of the second threaded section for defining two flanks therein. In this manner, both the first and the second threaded sections facilitate to sever and shatter cuttings so as to reduce the screwing resistance and prevent the object from being damaged under the accumulation of cuttings; simultaneously, the bimate screw effectively attains to a good resistance of extraction from the object by the concavities receiving the remaining cuttings which are not guided out of the object.

Abstract: The present invention pertains to a punch for forming recessed screw comprising a punch body and a punch head. Particularly, the punch head includes two square portions having different heights and square sides and intersecting at an included angle, thereby punching the corresponding tiers of recesses in the socket of the screw head. In this manner, the screw can be facilely driven by a screwdriver presenting a square configuration or a uniform shape as the punch, which facilitates to reduce the problem of unfitted driving tool and increase the convenience while in operation.

Abstract: A self-drilling screw includes a head and a shank having a drilling point defined at the distal end thereof; said drilling point further includes a first drilling section adjoining the threaded portion and a second drilling section adjoining the first drilling section. Two cut grooves are defined on the second drilling section and communicating with the first drilling section. Due to the two drilling sections, the making drill point dies are less damaged when shaping merely one section of drilling point. Besides, the smooth surface of the first drilling section provides space to put a trademark.

Abstract: A screw includes two types of threads which the first threads located close to the point of the shank and the second threads extend from the head of the screw, the two threads spiral in opposite direction. Said first threads have the outside diameter larger than the outside diameter of the second threads having a greater flank angle than the first threads so that the first threads can easily cut the fibers of the object and quickly merge into the object and the debris of fibers is heaped on the second threads which firmly fasten the screw in the object.

Abstract: A self-drilling screw is in particular to a drill portion having a non-threaded first drilling section connecting with the shank and a second drilling section connecting with said first drilling section and forms two grooves therein. Moreover, the whole first drilling section is formed as an oval-shaped pillar and it has two ridges extending therefrom. Furthermore, the diameter of the first drilling section is smaller than the diameter of the second drilling section, and the length of the second drilling section is between the length of one-third drill portion and the length of two-thirds drill portion. Therefore, due to the aforesaid features and the two drilling sections, the molds for manufacturing the screws suffer less damage while in operation and the manufacturing cost is therefore reduced. The present invention is also good at increasing the screwing speed. Moreover, the surface of the first drilling section also has the function of allowing the user to engrave a mark thereon.

Abstract: A screw includes a head and a shank which includes a thread defined in an outer periphery thereof and a tapered end section connected to a distal end of the shank. Two grooves are defined in the end section to form two cutting units and each cutting unit has a cutting edge and an extension portion. A cutting ridge extends from each of the two cutting units and an outer periphery of each of the cutting ridges intersects a circle whose diameter is composed of the cutting edges of the two cutting cutis. The cutting edges and cutting ridges share the torque so that the user use less force to screw the screw into an object and make the cutting ridges effectively cut the fibers of the object.