An enlarged head fastener device and method for manufacturing the same is described. The enlarged head fastener device includes a shank and a head. The head extends outwardly from the shank in a transverse plane to define a head periphery. The head has an anterior side and a posterior side. The anterior side includes a bearing surface and a convergent transition portion that reinforces the head. The convergent transition portion extends between a large end adjacent the bearing surface to a small end adjacent the shank. At least one ridge formation projects from the anterior side of the head providing additional reinforcement. The ridge formation extends continuously between an outboard end positioned on the anterior side of the head adjacent the head periphery and an inboard end positioned on the shank. The head maybe centered or offset relative to the shank.

A screw includes a head having a top surface where a drive socket and drive regions are recessedly formed. Each drive region has two non-parallel side walls and two different drive walls. One drive wall is connected to the side walls to form a groove communicating with the drive socket. The other drive wall is connected between two adjacent side walls of two adjacent grooves. At least one of the drive walls slopes downwards from the top surface at a slope of at least 1 degree. Each side wall connecting between the drive walls deviates inwards by an angle difference of at least 1 degree. The slope and the inward deviation of the walls receive a driving tool firmly to prevent a swinging problem and enhance the torque transmission. A punch adapted to form the recessed screw also facilitates a long-term production without losing the accuracy thereof.

A method and an apparatus for manufacturing a stepped member are provided. An intermediate portion of a shaft workpiece is radially enlarged while being compressed in an axial direction by applying alternating load to the intermediate portion in a direction intersecting the axial direction in a state in which pressure that compresses the shaft workpiece in the axial direction is applied to both ends of the shaft workpiece. The enlarged intermediate portion of the shaft workpiece is cat in a direction perpendicular to the axial direction so that the shaft workpiece is divided into two stepped members. Each of the stepped members has a shaft portion and a head portion provided at an axial end of the shaft portion, and the head portion has a larger diameter than the shaft portion.

A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure. The drive system comprises a fastener and/or bit having drive surfaces formed of either polygon involutes or a single arc construction. A punch is also provided for forming a recess in either the fastener or the bit, wherein the punch has corresponding surfaces.

The present disclosure relates to a pull stud bolt installation and removal tool for installing or removing a pull stud bolt (also referred to as a retention knob) onto or from a tool holder used in a machine tool, such as a machining center. The pull stud bolt installation and removal tool is a common product that is capable of properly restraining pull stud bolts of various types and specifications and is coupled with a torque wrench to accurately and safely tighten pull stud bolts to tool holders and jigs at desired locations with a specified torque.

The present disclosure relates to a pull stud bolt installation and removal tool for installing or removing a pull stud bolt (also referred to as a retention knob) onto or from a tool holder used in a machine tool, such as a machining center. The pull stud bolt installation and removal tool is a common product that is capable of properly restraining pull stud bolts of various types and specifications and is coupled with a torque wrench to accurately and safely tighten pull stud bolts to tool holders and jigs at desired locations with a specified torque.

Provided are a high-strength bolt having a tensile strength of 1,000 to 1,400 MPa and exhibits the same level of the delayed fracture resistance as that of the standard alloy steel even when omitting or reducing Mo and Cr from the SCM steel and the SCr steel, a steel wire for bolts used to manufacture such a high-strength bolt, and useful methods for manufacturing them. The steel wire for bolts in the present invention satisfies the predetermined chemical composition. When a rate of a B content at D.sub.0/4 part in the steel wire for bolts is 100% where D.sub.0 is a diameter of the steel wire for bolts, a ratio of a B content at a surface of the steel wire for bolts is 75% or less on average, and a difference between a maximum value and a minimum value of the ratio is 25% or less. A prior austenite crystal grain size number in a region from the surface to a depth of 100 m of the steel wire for bolts is No. 8 or more.

Provided are a high-strength bolt having a tensile strength of 1,000 to 1,400 MPa and exhibits the same level of the delayed fracture resistance as that of the standard alloy steel even when omitting or reducing Mo and Cr from the SCM steel and the SCr steel, a steel wire for bolts used to manufacture such a high-strength bolt, and useful methods for manufacturing them. The steel wire for bolts in the present invention satisfies the predetermined chemical composition. When a rate of a B content at D.sub.0/4 part in the steel wire for bolts is 100% where D.sub.0 is a diameter of the steel wire for bolts, a ratio of a B content at a surface of the steel wire for bolts is 75% or less on average, and a difference between a maximum value and a minimum value of the ratio is 25% or less. A prior austenite crystal grain size number in a region from the surface to a depth of 100 m of the steel wire for bolts is No. 8 or more.

Various embodiments described herein provide a fastener system having straight walled driving surfaces that provides a reliable stick fit feature, while also improving stability of engagement between the system components. A feature of the new system is to allow stick fit engagement of existing standard straight walled drivers in the new system.

A recessed fastener includes a head with a top face and a drive socket, a shank extending downward from the head, and threads helically around the shank. The drive socket has a bottom and drive walls extending upward therefrom. The bottom meets the drive walls at a bottom border. The drive walls meet the top face at a top border. The bottom border and the top border have respective first and second corners. The first corners are rotatably offset relative to the second corners. A joining line is connected between each first corner and each second corner, and one drive wall formed between two adjacent joining lines is in a spiral form. The spiral drive walls leads a driving tool toward the bottom to produce an automatic downward pressing force which facilitates the close engagement, thereby obtaining a quick driving operation, an increased driving power and a labor-saving effect.