The influence of design and technological factors on the durability of the installed carbide explosion equipment of three-cone drill bits

Abstract

Aim. In the study learning trial was made to make a mathematical model of the assembling process in connections " tungsten carbide insert cutter - cone", while the methods of mathematical statistics were applied. This makes it possible to determine the parameters of the distribution of the closing link. Accordingly, the tension is determined by samples of constituent links. For this purpose, the amount of tension was investigated. Tension affects the change in stress, which characterizes the accuracy of the assembly on the strength of the connection " tungsten carbide insert cutter - cone ". Depending on the magnitude of the insert pressing force, it is customary to estimate the tension in the connection. Method. The analysis of tungsten carbide insert cutter and holes in the layers of bit established that the size errors of the component links of dimensional chains are distributed according to laws that they are similar to the normal law of the distribution of random variables. The test was carried out according to the criteria of Pearson and Kolmogorov Results. The increase in pressing force with an increase in tension is due to an increase in elastic deformation both in the cemented layer and in the core layers of the rolling-cutter row. The extreme nature of the dependence of the pressing force on the amount of tension for the connection " tungsten carbide insert cutter - cone " has been established. This dependence, as a characteristic of the strength in the connection, can be used to design technological pressing operations for roller cone bits steels with different strength indicators. Scientific novelty. a mathematical model of the assembling process of connections " tungsten carbide insert cutter - cone " was made. It makes it possible to determine the parameters of the distribution of the closing link - tension, based on the samples of the component links. The established dependencies make it possible to reasonably and most accurately approach the formation of selective groups of teeth and the marking of holes for them. Practical significance. The appointment of tensions, the value of which exceeds the value of the extreme point, causes the occurrence of unfavorable plastic deformation or destruction of the layers of the shell (which are conjugated along the height of the shank of the insert cutter). They also result to the occurrence of irrational stresses in the body of the tungsten carbide insert cutter. It was established that the tension values have a greater influence on the force of pressing carbide teeth into the holes of roller cone bits steel 9310H (USA), when its hardness value is Rockwell hardness 59-60 compared to Rockwell hardness 48-50. Within the limits of the studied tension values, this dependence is linear.