Abstract: A peel type blind rivet (1) has a rivet body (2) composed of a cylindrical part (3) and a flange-shaped head (4) formed integral with one end of the part, and a mandrel (5) composed of a body (6) for insertion in the part and an enlarged head (7) formed at one end of the body. Radial blades (9) are formed integral with a lower surface (8) of the mandrel head such that the other open end (14) of part (3) will be cut into radially protruding split feet (14a) when the mandrel body (4) is pulled back. The mandrel head (7) is of a maximum diameter (D) greater than an outer diameter (d) of the cylindrical part (3). The lower surface (8) increases its diameter gradually and upwards from the mandrel body (6) towards a rim (7a) of the mandrel head having the maximum diameter. Each blade (9) is of a V shape protruding downwards from the lower surface such that a cutting edge (10) of each blade extends upwards and obliquely from the mandrel body towards the rim.

Abstract: A screw with a recessed head (3) has a crossing recess (4) formed in a top of the head and consisting of a central region (5) and four grooves (6) extending radially from the central region. Each groove is tapered to reduce width towards an outer conical bottom (9), which defines the groove together with opposite side walls (7, 8) transmitting torque. The bottom connecting outer edges of the side walls has a width ‘A’ larger than width ‘a’ in the widely used standard recesses of the same length ‘M’. The side walls have a radial length ‘B’ smaller than ‘A’, and distance ‘C’ between the intersections of two side walls of different grooves is equal to or larger than the product of 1.5 and ‘A’. One side wall (7) lies in a flat plane in parallel with the screw's axis, and is located forward in a tightening direction of the screw. The conical bottom (9) slanted 5° relative to the axis provides a conical sticking surface.

Abstract: A screw-driving apparatus has a sprocket (21) causing the belt (70) to intermittently advance, and the sprocket is rotatably held on a transverse shaft (26) supported in a side wall of a slider (2) perpendicularly to a driver bit (7). The sprocket (21) is driven by a ratchet wheel (22) rotated by a pawl (24) swingably connected to a bell crank (23), the ratchet wheel (22) coaxial with the sprocket rotating only in one direction along with the sprocket. The bell crank (23) located near the sprocket is rockably held on the slider (2) and its one arm normally protrudes upwards to engage with a shoulder (35) formed in an upper wall of a casing (1), and the pawl (24) is pivoted to the bell crank's other arm.

Abstract: A spike (10) for attachment to baseball shoes has a spike body (11), a leg (14) protruding upright from the spike body and having a distal edge (14a) and an abrasion-resistant tip (20) made of a metal and having a base portion welded to the distal edge of the leg. The base portion (21) has a wedge-shaped ridge (22) pressed to an end face of the distal edge such that the base portion (21) is gripped by and between masses of a once molten and then resolidified material of the distal edge of the leg, so that the spike is abrasion resistant and durable. The distal edge (14a) may have at its middle region a cutout (16) to divide the end face into two parts to which the base portion (21) of the tip are adjoined concurrently and in the same manner.

Abstract: A belt (10) has cylinders (12) formed integral with a body (11) to hold a row of self-drilling reaming screws (20) each having a head (25), a threaded shank (21), a drill tip (22) and reaming blades (23) disposed on the tip and near the shank. The belt further has slits (13) extending radially from each cylinder, and lateral cutouts (15) intermittently drive the belt at the same pitch as the cylinders. Each cylinder is prismoidal between its wider inlet and narrower outlet so that a distance A between the cylinder's walls gradually decreases towards the outlet, but at the inlet this distance is substantially equal to the diameter d.sub.1 of an envelope circle of the blades. Inner edges (13a) of the slits (13) facing one another and disposed in and from the regions' inlet sides are spaced also the same distance B as the diameter d.sub.1 so that each screw can take a correct position on and perpendicular to the belt, thus enabling it to be loaded with the screws smoothly and efficiently.

Abstract: A screw-holding belt (10) is composed of a belt body (11) made of a flexible plastics sheet, and cutouts (12) serving to intermittently drive the belt body are formed in and along either or both the lateral sides of the belt body. Screw-holding cylinders (13) are formed in the belt body at the same pitch as the cutouts so as to receive and hold shanks (17) of headed screws (16). The belt further has apertures (14) formed in it and extending outwardly and radially from the opening of each cylinder (13), and each aperture (14) is of a sector form having a width increasing towards its bottom (14a) such that these bottoms are portions of an imaginary circle coaxial with the cylinder and having a diameter greater than that of a head (18) of each screw (16). The adjacent two apertures (14) define between them a skirt (15) whose circumferential width decreases towards the imaginary circle.

Abstract: A recessed screw has a recess formed in the head of screw, with the recess being defined as a superimposition of two equilaterally-triangular recesses each having vertices shaped arcuate and arranged coaxially with a phase shift of 60.degree. around the screw axis. The recess thus has alternating six grooves and six driven vanes having side walls extending parallel with the axis, and an inner ridge of vane is a conically curved sticking wall inwardly slanted towards a bottom of the recess. A cross-sectional area of groove is larger than that of each vane. A driver bit has six driving vanes in conformity with the grooves and six valleys each interposed between the adjacent driving vanes and corresponding to the driven vanes in the recess, such that a biting action appears between the recess and bit, the driving vanes can be strengthened, and any conventional bit for Torx screws can be used with the recessed screw.

Abstract: A metal rod (20) having a conical or pyramidal cut extremity (20a) is used to make a mandrel for blind rivets. The rod is held in place between a pair of die segments (11) such that its end (26) of a preset length, including the tip protrudes from an upper surface (14) of the segments. Subsequently, a free intermediate portion of the swageable end (26) is axially compressed to form a mandrel head (27) by a punch (12) which has a lower face (17) parallel to the upper surface (14) of the segments with a conical or pyramidal recess (18) formed on the end. The free intermediate portion of the swageable end (26) swells radially outward to form the head (27) having a flat flange (31) from which the tip intrudes. The mandrel, which has the head formed uniformly without any eccentricity about the longitudinal axis of a mandrel body, can be produced inexpensively using a prior art nail manufacturing apparatus.

Abstract: A driver bit adapted to engage in a recess of a recessed screw which recess is defined as a coaxial superimposition of two equilaterally triangular and cylindrical recesses each having arcuate vertices and arranged with a phase shift of 60.degree. about a center axis of the recessed screw to provide six engagable grooves and six driven vanes. The driver bit includes six driving vanes and six valleys, with each driving vane being shaped in conformity with each groove in the recess of the recessed screw, and with each valley being interposed between adjacent driving vanes and shaped in conformity with each driven vane in the recess of the recessed screw.

Abstract: A concrete anchor has an anchor body 21, which is a rod-shaped member 22 having a male thread 23 and a striking head 24, both formed at one end of the member. This rod-shaped member 22 further has at its another end a cylindrical portion 25 so that slots 26 extend axially from an open end of the portion so as to provide expandible feet 27. Saw-toothed scratching tips 28 are formed to be acute ends of the expandible feet. A tapered plug 31 which is inserted in the cylindrical portion 25 has an annular recess 34 and a retaining shoulder 36, both formed between a large diameter portion and a root 35 of the tapered plug, with the annular recess providing a cavity to receive concrete scrapings, so that an impact applied to the striking head can provide a strong and effective retention force for the concrete anchor, and any cracks which may be produced around a hole holding the fixed anchor does not impair the retention force.

Abstract: A method of making an elongated mandrel having an end integral with a drill section, with the method including the steps of subjecting a single columnar piece of material to the heading process so as to make a blank N composed of the mandrel, a short stem having one end integral with the end of the mandrel and having a diameter D greater than a diameter of the mandrel, and a flange formed integral with the other end of the stem. The short stem is then cold forged to produce the drill section having end edges (7a) and (7b) facing the flange, and, subsequently, the drill section is trimmed so as to remove the flange together with a scrap resulting from the cold forging of the stem, in such a manner that the mandrel having the integral drill section can be mass produced from the single piece of raw material, efficiently at a reduced cost.

Abstract: A recessed screw having in its head a recess for engaging with a driver bit, with the recess being defined with curved engaging walls and radial or corner grooves. Each engaging wall is a portion of a conical surface slanted inwardly towards a bottom of the recess. Each corner groove extends outwards from the adjacent engaging walls in radial direction. A pair of vertical side walls, lying parallel with the recessed screw's axis define each corner groove. The driver bit has protrusions tightly fittable in the recess, which recess may be a superimposition of two square holes disposed symmetrically with a phase shift of 45.degree. around the axis so as to provide eight corner grooves. Each engaging wall may be formed at a place where the side walls intersect one another. The driver bit may comprise a shank and a bit portion which extends from the shank and formed with eight V-shaped grooves extending axially of the bit so that eight blades are defined each between the two V-shaped grooves.

Abstract: An anchor bolt having a spring member is provided, with the anchor bolt comprising a fastening sleeve, an expansion sleeve and an expansion body. The spring member is interposed between the fastening sleeve and the expansion sleeve, and the expansion body is disposed at one end portion of a threaded rod formed as an anchor main body and is adapted to be inserted deep in a hole of a concrete structure together with the threaded rod. The said fastening sleeve and spring member are loosely fitted on the threaded rod, wherein the fastening sleeve adapted to be fixed within an inlet portion of the hole compresses the spring member to urge the expansion sleeve toward the expansion body so as to be expanded thereby, thus preventing the anchor bolt from being removed from or being loosened in the hole. The fastening sleeve preferably comprises an opening through which an end portion of the spring member extends to be exposed for visual inspection.

Abstract: A breakable composite drill screw comprises a first shank made of a metal unsusceptible of hardening, a driving head extending from one end of the first shank and engageable with a screw driving tool, a second shank made of another metal susceptible of hardening, the second shank being fixedly adjoined to the other end of the first shank to thereby provide a break zone at said other end, a drill bit formed by cold forging at an end of the second shank, a continuous thread formed by thread-rolling to extend around both outer cylindrical peripheries of the first and second shank wherein a portion extending from the break zone to the drill bit is hardened or quenched, and wherein said shanks are adjoined at their engaging surfaces to each other by projection-welding technique making use of a welding lug protruding from either engaging surface, said lug forming the break zone.