A die matching system which is preferably implemented in die rolling machinery for fasteners employs witness or reference marks on each of the dies. An eddy current sensor is employed to sense the witness marks and to detect change in the relative position of the witness mark and hence the position of the rotatable dies. The change in position is then processed and a signal is transmitted to servo motors to change the relative position of the dies to compensate for the position changes continuously during the operation of the die rolling machinery. In one preferred form, the witness mark is in the form of a recess milled into the bottom end surface of the cylindrical die.

A bottle-shaped can in which flatness and circularity of a neck portion are improved. An upper incomplete thread portion is formed at an upper end of a thread. A height of the upper incomplete thread portion is shorter than an average height of the thread, and increases gradually toward the average height. A length of the upper incomplete thread portion between a first point and a second point is set in such a manner that an angle between a line drawn between the first point and a center point of the neck portion, and a line drawn between the second point and the center point of the neck portion falls within a range from 20 degrees to 60 degrees.

Provided is a method for performing an external pipe thread process on a hollow blank by at least twice rolling, wherein amount of rolling wheels in a rolling wheel set, used in any two back-to-back rolling processes in a processing sequence, are different in parity. Further provided are various roll-processing modules and corresponding rolling apparatuses, achieving the above processing method and having a simple structure, portability and practicality. A hollow blank is not liable to deform when performing an external pipe thread rolling process thereon, thereby improving a processing yield.

Provided is a method for performing an external pipe thread process on a hollow blank by at least twice rolling, wherein amount of rolling wheels in a rolling wheel set, used in any two back-to-back rolling processes in a processing sequence, are different in parity. Further provided are various roll-processing modules and corresponding rolling apparatuses, achieving the above processing method and having a simple structure, portability and practicality. A hollow blank is not liable to deform when performing an external pipe thread rolling process thereon, thereby improving a processing yield.

The invention relates to a connecting element (10, 30) for connecting at least two components that are positioned one on top of the other, comprising a shaft (14, 34) and a head (12, 32), which is provided with a drive (38), the shaft (14, 34) being formed from a base material and ending at the exposed shaft end thereof that is opposite the head (12, 32). The invention is characterised in that a tip (16, 40) made of plating material is applied to the exposed shaft end, which plating material is different from the base material.

A method for forming a stop flange on a self-tapping screw includes locating a shank of a self-tapping screw between two threading dies, fixing one of the two threading dies and moving the other one of the two threading dies to work the shank, the external thread forming section of each of the threading dies performing threading to form an external thread on the shank, inserting the insert and the recessed corner of each of the threading dies into a top of the external thread to form a groove in the shank, and the insert of each of the threading dies gradually squeezing downward an extruded portion that is formed during formation of the groove to form a stop flange on the shank. Thus, the shank is integrally formed with the stop flange, to stop an excessive movement of the external thread.

A fastener with a body with a shank, a head adjacent one end of and integral with the shank, and a shoulder adjacent the head, and a separate washer with a through hole received on the shank, bearing on the shoulder and securely fastened to the shank. The body and washer may have an interference fit. The body may be made and the washer attached by cold forming the body with a ring bearing on the washer.

In a method for producing a connecting element, in particular a bolt, a zinc anti-friction coating is applied to a blank made of a metallic base material. Subsequently, the coated blank is deformed in a deformation process to a desired final geometry of the bolt. The deformation process may, in particular, be a thread rolling process. The anti-friction coating is applied in particular by way of a zinc diffusion method. The bolt is in particular an engine bolt, specifically a connecting rod bolt. A bolt of this type has a durability as conventional bolts, but at the same time can be mounted repeatedly by virtue of the formation of the special anti-friction coating without the coefficients of friction increasing above permissible limits.

In a method for producing a connecting element, in particular a bolt, a zinc anti-friction coating is applied to a blank made of a metallic base material. Subsequently, the coated blank is deformed in a deformation process to a desired final geometry of the bolt. The deformation process may, in particular, be a thread rolling process. The anti-friction coating is applied in particular by way of a zinc diffusion method. The bolt is in particular an engine bolt, specifically a connecting rod bolt. A bolt of this type has a durability as conventional bolts, but at the same time can be mounted repeatedly by virtue of the formation of the special anti-friction coating without the coefficients of friction increasing above permissible limits.

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.