Abstract: A cubic boron nitride sintered material comprises cubic boron nitride particles and a bonding material, wherein the bonding material comprises at least one first metallic element selected from the group consisting of titanium, zirconium, vanadium, niobium, hafnium, tantalum, chromium, rhenium, molybdenum, and tungsten; cobalt; and aluminum; the cubic boron nitride sintered material has a first interface region sandwiched between an interface between the cubic boron nitride particles and the bonding material, and a first virtual line passing through a point 10 nm apart from the interface to the bonding material side; and when an element that is present at the highest concentration among the first metallic elements in the first interface region is defined as a first element, an atomic concentration of the first element in the first interface region is higher than an atomic concentration of the first element in the bonding material excluding the first interface region.

Abstract: In a spot welding gun which is made up of a gun main body which is operated for equalization by a driving source, a stationary electrode tip which is immovable relative to the gun main body, and a movable electrode tip which is connected to a pressing source, both electrode tips are pressed to a workpiece with an even force, to thereby perform a high quality spot welding. The driving source is controlled such that the electrode force of the stationary electrode tip, by the driving source, to the workpiece becomes substantially zero. In this manner, there occurs no difference in the electrode forces by both the electrode tips to the workpiece.

Abstract: A workpiece is welded successively at a plurality of welding points by a direct-current resistance welding machine with a constant current in a welding current supply period at each of the welding points, and the constant current is varied depending on whether expulsions are produced on the workpiece when it is welded, to determine an expulsion-producing limit current value as a maximum current beyond which expulsions will be produced. The workpiece is welded with a first stepped welding current having a first current value that is smaller than the expulsion-producing limit current value by a predetermined value and a second current value that is greater than the expulsion-producing limit current value, and an average current value higher than the expulsion-producing limit current value, and also with a second stepped welding current having a variation of the second current value based on whether expulsions are produced or not on the workpiece when it is welded with the first stepped welding current.

Abstract: A nut runner control system includes a plurality of nut runners, a plurality of subcontrollers connected to the nut runners, respectively, for controlling the nut runners, and a master controller connected to the subcontrollers for presetting and modifying drive conditions for the nut runners and for monitoring the nut runners based on data indicating operating conditions of the nut runners and received through the subcontrollers, respectively.

Abstract: A screw equipped with locking means, includes a female thread made of a synthetic resin and a male thread made of a metal, or a female thread made of a synthetic resin and a male thread made of a synthetic resin, fitted with each other, the female thread having a double cylindrical boss portion formed at the center thereof so that the male thread may be fitted into the innerside boss portion and the thread portion of the boss may be deformed more or less when pressed against the shaft of the male thread in the direction perpendicular thereto through the resilience of the synthetic resin, which is the material of the female thread, by pressing the terminal end of the innerside boss portion against the flange portion of the male thread or a member to be fixed at the final stage of clamping the screw. A female threaded nut may have a blind bore with a projection at the bottom for engagement and deformation by a cutter on the end of a bolt.