The Influence of Technological Factors on the Reliability Connection for Tungsten Carbide Inset Cutter of Roller Cone Bits

Aim. Analysis of used bits revealed the effect when the tungsten carbide insert cutter was scrolling around its axis. Therefore, the task was to study the causes of this phenomenon. Hardness was measured followed by setting the hardness distribution gradient in the section of the hole, in order to evaluate the strength parameters of steel in the zone of the hole. Method. Applying a well-tested method, namely the method of successive approximations, we determined the estimate of the standard deviation and the evaluation criterion. Sample averages were checked for homogeneity. For this, we evaluated the character and magnitude of the difference between adjacent sample means. In conducting such an analysis, Student's t test was applied. Results. The obtained data allow us to establish a fact, that the cutting speed within the studied limits does not significantly affect the breakdown’s size of the holes when unfolding the holes in the body of the cones for fitting tungsten carbide inset cutters. The impact of technological parameters on the statistical association between the magnitude of the hole deployment and roughness for the processing surfaces was also studied. Scientific novelty. The analysis showed that the planes of sliding are formed along the neutral lines of tension - compression in the section of the working wedge surface of the tungsten carbide inset cutter. Under adverse conditions, the distribution of stresses in the conjugation "inset cutter - hole" is the sudden emergence of the spread of trunk cracks. This leads to the sudden destruction hard alloy of the inset cutter. Therefore, the accuracy of the connection is crucial. Practical significance. The ovality of the holes must be reduced to 0.02 mm, If you increase the tolerance around the hole, then there is an unfavorable voltage distribution. This leads to the destruction of the conjugate elements of the inset cutter and the hole of the rolling-cutter row. It is necessary to take into account the character of the stress distribution in the closely spaced not only two inset cutters, but groups of inset cutters in the rolling-cutter row.