The present invention provides a looseness-prevention screw thread structure including a screw thread having a predetermined pitch, a no-load flank which is an inclined surface in a direction in which the screw thread is advanced, and a load flank which is an inclined surface in a direction in which the screw thread is retracted, the no-load flank and the load flank being formed at both sides of the screw thread, in which the no-load flank of the screw thread includes: a first tangential portion which abuts against an arc portion formed at a thread crest of an opposing fastening object; and a second tangential portion which has a preset angle with respect to the first tangential portion and abuts against the arc portion.

A processing die and a preparation method for a fastener are provided. The processing die includes a punch and a die. The top of the punch and the bottom of the die are configured for being connected with a hydraulic press, the die includes a first half die and a second half die which are clamped to form an inlet channel, an expansion corner channel and a torsion channel, and an extrusion channel is included in the forming sliding block, the inlet channel, the expansion corner channel, the torsion channel and the extrusion channel are sequentially assembled to form a die channel cavity, and a billet to be processed is successively subjected to upsetting, shearing, torsion and extrusion in a single die under the pressure of the punch.

A processing die and a preparation method for a fastener are provided. The processing die includes a punch and a die. The top of the punch and the bottom of the die are configured for being connected with a hydraulic press, the die includes a first half die and a second half die which are clamped to form an inlet channel, an expansion corner channel and a torsion channel, and an extrusion channel is included in the forming sliding block, the inlet channel, the expansion corner channel, the torsion channel and the extrusion channel are sequentially assembled to form a die channel cavity, and a billet to be processed is successively subjected to upsetting, shearing, torsion and extrusion in a single die under the pressure of the punch.

A method of manufacturing a drill comprises providing an elongate element defining a longitudinal direction and having, in the longitudinal direction, a front end, an intermediate section, and a rear end opposite to the front end; forming by cold forming only, at the front end, a drill tip having a cutting edge; and, forming by cold forming only, on the intermediate section, a channel extending along the longitudinal direction.

The invention relates to a method for producing a gland or a gland blank (3), the method comprising a step of producing a blank (3) having a cylindrical shaft (5) formed on a screw head (4), and a blind hole (7) being formed in the blank (3) from an upper side (11) of the screw head (4) facing away from the shaft (5) in a, in particular further, method step, the blind hole (7) extending toward the shaft (5) and forming at least one first section (13), in particular having a polygonal cross section (Q1), preferably for receiving a screw tool. The blind hole (7) is deepened, thus forming at least one second section (14), which borders the first section (13), in a subsequent method step, the second section (14) forming a preferably at least partially continuous cross section (Q2) which is in particular smaller in size than the first cross section (Q1), the shaft (5) being widened in sections, thus forming an undercut (15) at the crossover between the shaft (5) and the screw head (4), in particular by at least indirectly displacing material from at least the second section (14) of the blind hole (7), in the subsequent method step.

A rolled thread screw includes: a screw part having, on an outer circumferential part of the screw part, thread crests and thread grooves disposed alternately along an axial direction of the rolled thread screw; and a columnar part adjoining at least one of both sides of the screw part in the axial direction. An axial end surface of the columnar part is provided with: a first concave surface concave in the axial direction; a second concave surface positioned to an outer circumference of the first concave surface and being concave in the axial direction; and a salient part positioned on a boundary between the first concave surface and the second concave surface and projecting further than a bottom of the first concave surface and a bottom of the second concave surface, the salient part extending in an arc-like shape along a circumferential direction of the columnar part as viewed in the axial direction.

A method for producing a screw foundation for securing elements in the ground, provides a cylindrical tube as an initial form and a conical front portion tapering to an insertion tip is then molded on to the cylindrical tube using a non-cutting process, the front portion being provided at least in some regions with a thread-like contour for screwing into the ground. An inner contour for a screwing tool is formed integrally in a rear end of the tube by flow forming, and the front portion and the thread-like contour are formed exclusively by flow forming.

A bolt and a method for manufacturing the bolt are provided. The bolt includes a screw cap and a bolt bar, the bolt bar includes a positioning bar, a flexible bar and a threaded portion, the positioning bar is connected to one end of the screw cap, and the flexible bar is connected to the positioning bar and the threaded portion respectively. Wherein, an anti-shearing stand is formed on the flexible bar. The threaded portion includes standard threads and transition threads, the transition threads are formed between the flexible bar and the standard threads, and a thread height of the transition threads is smaller than a thread height of the standard threads, wherein the thread height of the standard threads keeps constant. The force distribution of the threads can be optimized, and the threads can effectively cooperate with the threads of the nut.

A bolt and a method for manufacturing the bolt are provided. The bolt includes a screw cap and a bolt bar, the bolt bar includes a positioning bar, a flexible bar and a threaded portion, the positioning bar is connected to one end of the screw cap, and the flexible bar is connected to the positioning bar and the threaded portion respectively. Wherein, an anti-shearing stand is formed on the flexible bar. The threaded portion includes standard threads and transition threads, the transition threads are formed between the flexible bar and the standard threads, and a thread height of the transition threads is smaller than a thread height of the standard threads, wherein the thread height of the standard threads keeps constant. The force distribution of the threads can be optimized, and the threads can effectively cooperate with the threads of the nut.

A hollow screw and related process of making is provided, wherein the hollow screw is formed from a generally circular corrosion resistant stainless steel disk cut from flat roll stock. The hollow screw includes a head and an elongated and hollow shaft having a wall thickness between about 0.2 to about 0.7 millimeters extending therefrom and defining a shank portion and a threaded portion having a plurality of threads thereon with a rotational drive mechanism configured to facilitate tightening via the threads. The process involves annealing to soften the stamped hollow screw, followed by thread rolling, and then age hardening the hollow screw. As such, the resultant hollow screw is relatively lightweight, about 50% the mass of a solid core screw made from the same material, with a sufficient thread strength to meet most aerospace applications and contributes to important aircraft fuel economy.