Automated system for ultrasonic press-fitting of rolling cutter bit teeth

Abstract

Questions are considered for improving the efficiency of press-fitting rolling cutter bit teeth based on using high-frequency low-amplitude ultrasonic vibrations that intensify the assembly processes. A computer automated system is developed for scientific studies of the process of ultrasonic assembly (ultrasonic press-fitting) of hard alloy bits with simultaneous diagnosis of quality indices for the joint formed. Experimental studies are performed for the press-fitting force and strength properties of joints assembled by traditional methods and with the action of ultrasound that have shown a reduction in press-fitting force by up to 20% with a simultaneous increase in strength by 5%.Premature failure of drill bits and the existence of a reduction in drilling efficiency occurs due to crack formation within the body of a rolling cutter, in rings and the inter-ring space in zones of press-fitting teeth into a hole, particularly in rolling cutters of small diameter. Microcracks, that arise during tooth compaction are transformed into macrocracks with hundreds of thousands of loading-unloading cycles with loads from zero to the maximum during action of teeth on rock which leads to rolling cutter breakage and accidents during boring.Contact bonds that form during tooth compaction govern, on one hand, the force and accuracy parameters of the production process itself for joining components and, on the other hand, operating indices of the assembled rolling cutters. Control of assembly and engineering monitoring of the joints formed is traditionally accomplished by measurement of forces and moments applied to a component, and their coordinates with respect to the relative movement of teeth during press-fitting.The main complication in organizing management of press-fitting is connected with production and assembly errors that relate to deviations of dimensions, shape and surface roughness for assembled components, inaccuracy of the reciprocal position of assemblies with units for assembly position, disturbance of assembly conditions, inaccuracy in functioning of assembly equipment, etc. In Volgaburmash and SamGTU, research work has been carried for determining the optimum parameters for locating teeth in rolling cutter rings, and finite element methods have been developed making it possible to

Ultrasonic excitation during press-fit joining of electrical contacts

“…In Ref. [3], teeth were inserted in rolling cutters with ultrasonic assistance. The press-in force could be reduced by 20%.…”

Enhancing the Retention Force of Press‐Fit Connections by Ultrasonic Excitation

“…In Ref. press‐fitting was combined with ultrasound to insert teeth in rolling cutters. A 5% higher strength was obtained.…”