Abstract: In a washer, a central opening is provided for receiving a screw. This large surface-area washer comprises a flat edge area extending so as to be closed with a convexly curved portion adjoining the latter. The central opening is defined by a wall which is conically shaped or comprises one or more steps. The washer serves to fasten parts to an underlying structure, particularly to fasten single-layer or multiple-layer roofing with insulating material on a fixed underlying structure.

Abstract: A tapping screw includes a screw head, a self-tapping thread portion and a drilling point. The drilling point has a pair of approximately axially extending flutes which are located diametrically opposite each other relative to the shank axis and include clearing surfaces and cutting surfaces. The cutting surfaces end in cutting edges facing the point of the screw and lateral outer knives. Immediately adjacent the cutting edges or cutting knives, the cutting surfaces have a convexly arched cross-sectional shape.

Abstract: A fastener assembly for securing roofing on soft insulation material to a solid base is formed of an axially elongated screw and a large surface washer. The screw has an elongated shank with a cutting tip at one end and a screw head at the other. A self-cutting thread is formed on the shank. The shank has a thread-free section extending from the screw head. The thread-free section has a diameter not greater than the diameter of the opening in the washer into which the screw is inserted. The washer has a countersunk area around the screw opening to receive the screw head in a recessed manner. The shank of the screw, at a spaced distance from the screw head and in the axially extending region of the thread-free section has a stop or similar member which forms a support for the washer. With the assembly secured to the solid base, the washer is tiltable relative to the screw. Accordingly, the fastener assembly can be stepped on without any damaging transfer of stress from the washer to the screw.

Abstract: A self-drilling screw includes an axially extending screw shank with a leading end and a trailing end. A drill bit is secured to and extends axially outwardly from the leading end of the screw shank. At least one wing extends laterally outwardly from the drill bit transversely of the axial direction of the screw shank and spaced from the cutting edge at the leading end of the drill bit. The wing has a cutting edge facing toward the leading end of the drill bit. The wing extends outwardly beyond the outside diameter of the screw shank and forms an enlarged bore through which the shank can pass without contact with the surface of the larger bore. Each wing has a break-off groove or notch so that it can separate from the drill bit.

Abstract: Screw driving apparatus in which a slide is movable back and forth on a support and is formed with a chute extending in the slide away from the support toward an open end of the chute, and with an access opening to the chute. A driver is mounted on the support for rotation in the chute and for movement in the chute toward and away from the open end in response to the back-and-forth movement of the slide. The slide carries a control plate capable of limited movement relative to the slide between two terminal positions spaced in the direction of slide movement. Two jaws are pivotally mounted on the slide and may jointly obstruct the open end of the chute. A jaw operating member on the control plate engages the jaws and moves them toward and away from the chute-obstructing position in response to movement of the control plate between its terminal positions which is caused by motion transmitting elements on the support when the slide moves back and forth.

Abstract: An elongate supply ribbon of plastic material for supporting bolt-like fastener elements is structured with a back wall portion and a plurality of tongues extending from opposite sides of the back wall portion generally perpendicularly to the plane thereof. Bending regions interposed between the back wall portion and the tongues are formed with notches which have sides abutting each other when the tongues are bent to extend perpendicularly from the plane of the back wall portion in order to provide bearing support for the tongues.

Abstract: A self-tapping screw whose stainless steel shank has a slotted free end in which a plate-shaped, carbide drill bit is fastened, the bit being dimensioned and arranged to drill a hole smaller than the major diameter of the tapping threads.

Abstract: Automatic driving apparatus which sequentially inserts screws provided with washers into work pieces includes a chute formed with an opening transverse to its axis. Screws are fed sequentially through the opening into the chute. A driver in the chute is shaped for driving engagement with an introduced screw. A drive mechanism axially moves the driver in the chute and rotates the same in a plane transverse to the axis for thereby engaging the driver with the screw and axially moving the screw with the rotating driver. A magazine adapted to hold apertured washers is provided with a slide which sequentially moves the washers transversely to the chute axis from the magazine to a position of alignment of an aperture in the moved washer with an axially moving screw in the chute. A source of motive power is connected with the feeding mechanism for the screws, the drive mechanism, and the slide for transmitting motive power to the feeding mechanism, the drive mechanism, and the slide in timed sequence.