In blast hole drilling, it is desirable to be able to drill as close as possible to the edge of the tunnel. The minimum distance from the edge is defined by the radial size of the rockdrill. Most of the rock drills used today have a rotation motor that rotates an axel parallel to the shank, which further rotates the shank through a gear set. Thus making the rock drill bulky.
This thesis project carried out at Atlas Copco Rock Drills AB, Örebro, deals with the rotation mechanism of a rock drill. The main task of the project was to develop alternate concepts for rotation mechanism that would use the shank as a part of rotation mechanism and reduce the bulkiness of the rock drill.
In order to find a suitable alternative, eight different concepts for hydraulic motor (with or without transmission) were generated and evaluated against each other. Two concepts, 1) multi-cam vane motor concept and 2) strain wave hydraulic gear motor concept, were selected for further functional design. Both concepts were designed at ideal conditions (100% efficiency) to achieve the required displacement.
For the multi-cam vane motor, various design improvements were performed and the effect of different design parameters were also analyzed. Different variants of the motor were developed and analyzed. A rough design was performed for the strain wave hydraulic gear motor concept which was chosen for its novelty. CAD models for both the concepts and the related variants were developed for suggesting assembly layouts and valve mechanisms. The two concept designs would reduce the bulkiness of the rock drill. The benefits and drawbacks of the different variants have been discussed. The concepts must be further developed for implementation into a rockdrill.
Author: Bhaskar Reddy, Akepati