Abstract: A screw with a flat drilling end comprises a cylinder (1) with a thread (11) wrapped around and a flat drill portion (2) longitudinally extended from a distal end of the cylinder (1); a maximum thickness (T) of a transversal cross section of the flat drill portion (2) being less than a half of the maximum width (D) of the transversal cross section of the flat drill portion (2); the maximum width (D) of the transversal cross section of the flat drill portion (2) being smaller than an outer diameter of the thread (11) of the cylinder (1); the width and thickness of the transversal cross section of the flat dill portion (2) being reduced to a point tip end of the flat drill portion (2). Two opposite lateral sides form as sharp knife blades.

Abstract: A screw capable of drilling holes easily and discharging dregs effectively includes a head; and a stem. The head is formed by an upper portion and a lower portion. The upper portion is a round disk. The annular ring of the round disk of the head is formed with a plurality of inclined protrusions. Recesses between the protrusions extend from an inner edge of the round ring to an outer edge of the round ring and are arranged along un-radial paths. A periphery of the lower portion of the head is formed with at least one knife sheet which extends from the annular ring of the round disk of the head to the stem; and the direction of the knife sheet is inclined to an axis of the lower portion of the head. At a connection of the head and stem, the knife sheet has a maximum height and width.

Abstract: A screw capable of drilling holes easily and discharging dregs effectively includes a head; and a stem. The head is formed by an upper portion and a lower portion. The upper portion is a round disk. The annular ring of the round disk of the head is formed with a plurality of inclined protrusions. Recesses between the protrusions extend from an inner edge of the round ring to an outer edge of the round ring and are arranged along un-radial paths. A periphery of the lower portion of the head is formed with at least one knife sheet which extends from the annular ring of the round disk of the head to the stem; and the direction of the knife sheet is inclined to an axis of the lower portion of the head. At a connection of the head and stem, the knife sheet has a maximum height and width.

Abstract: A screw with a flat drilling end comprises a cylinder (1) with a thread (11) wrapped around and a flat drill portion (2) longitudinally extended from a distal end of the cylinder (1); a maximum thickness (T) of a transversal cross section of the flat drill portion (2) being less than a half of the maximum width (D) of the transversal cross section of the flat drill portion (2); the maximum width (D) of the transversal cross section of the flat drill portion (2) being smaller than an outer diameter of the thread (11) of the cylinder (1); the width and thickness of the transversal cross section of the flat dill portion (2) being reduced to a point tip end of the flat drill portion (2). Two opposite lateral sides form as sharp knife blades.

Abstract: A screw comprises an enlarged head; a large diameter screw rod having one end extending from the enlarged head; a small diameter screw rod having one end extending from another end of the large diameter screw rod; another end of the small diameter screw rod being formed as a tip end; a first thread extending from the large diameter screw rod and the small diameter screw rod; and the first thread extending to the tip end of the small diameter screw rod. A diameter of the first thread on the large diameter screw rod is large than that of the first thread on the small diameter screw rod. A pitch of the first thread on the large diameter screw rod is smaller than or equal to that of the first thread on the small diameter screw rod.

Abstract: A screw comprises an enlarged head; a large diameter screw rod having one end extending from the enlarged head; a small diameter screw rod having one end extending from another end of the large diameter screw rod; another end of the small diameter screw rod being formed as a tip end; a first thread extending from the large diameter screw rod and the small diameter screw rod; and the first thread extending to the tip end of the small diameter screw rod. A diameter of the first thread on the large diameter screw rod is large than that of the first thread on the small diameter screw rod. A pitch of the first thread on the large diameter screw rod is smaller than or equal to that of the first thread on the small diameter screw rod.

Abstract: A screw capable of drilling holes easily and discharging dregs effectively includes a head; and a stem extending from a lower portion of the head. The head is formed by an upper portion and a lower portion. The upper portion is a round disk. The annular ring of the round disk of the head is formed with a plurality of inclined protrusion. The recesses between the protrusions extend from an inner edge of the round ring to an outer edge of the round ring and are arranged along un-radial paths. A periphery of the lower portion of the head is formed with at least one knife sheet which extends from the annular ring of the round disk of the head to the stem; and the direction of the knife sheet is inclined to an axis of the lower portion of the head.

Abstract: A flat drill end of a screw mainly includes a cylinder with a drill end having a thread wrapped around the cylinder, and a flat drill portion formed to the cylinder along to the drill end of the cylinder with a predetermined length. The thickness of the flat drill portion is less than a half of the width of the flat drill portion for receiving more debris and ejecting the debris during the drilling so as to form a drill screw capable of drilling fast and preventing split on to the working piece.

Abstract: A chain strip for guiding screws in an auto-locking screwdriver comprises at least two papers, the two papers being adhered to one another intermittently, so as to form a plurality of holes between the two papers, wherein screws can be installed in the holes. A first paper of the at least two papers is a wave-like paper layer with protrusions. A second paper of the at least two papers is also a wave-like paper which has a shape identical to the first paper. The first and second papers have a shape selected from semi-round shapes, rectangular shapes, cambered shapes, and trapezoidal shapes. Each connection area has a driving hole for driving the chain strip to move. In use, two chain strips are arranged, and screws pass through the holes of the two chains.

Abstract: The present invention discloses a dynamic pressure bearing device, comprising a bearing, an axial hole passing through the bearing, a plurality of dynamic pressure generating grooves extended along the axial direction and disposed on the periphery of the axial hole. The dynamic pressure generating groove comprises a fluid lubricating medium therein, and these dynamic pressure generating grooves comprise a base section extended along the axial direction, and a lateral section is expanded and extended from both ends of the base section, and these lateral sections are curved in shape, such that when the axle center rotates in the bearing, the fluid lubricating medium originally disposed at the lateral section will flow towards the base section and concentrate at the base section to have a slightly protruded shape as to press against the axle center for rotating the axle center stably.

Abstract: The present invention discloses an improved dynamic pressure bearing assembly, comprising a bearing, an axial hole passing through the bearing, a plurality of aslant planes milled by a milling machine and extended along the axial direction and disposed on the periphery of the axial hole, and a dynamic pressure generating groove disposed among the planes. The dynamic pressure generating groove comprises a fluid lubricating medium therein, and thus the periphery of the axial hole can be manufactured on the planes very easily, and thus not only making the manufacturing easier, but also providing the required precision. Further, the present invention can evenly eject the fluid contained in everywhere inside each dynamic pressure generating groove towards the axle center by the drag of the centrifugal force, and further fix the axle center in place and maintain the axle center at the central position in the bearing.