Shank adapter, rock drilling machine and method
A shank adapter, rock drilling machine and method of mounting a shank adapter of a rock drilling machine inside a slide bearing element. The shank adapter includes a coupling head and a rotation portion at its opposite ends, and a flushing portion located therebetween. Outer diameters of the coupling head and the rotation portion are both greater than outer diameters of portions of the shank adaptor located therebetween.
1. A rock drilling machine, comprising:
a body;
an impact device arranged for generating impact pulses;
a shank adapter arranged for receiving the impact pulses and transmitting the impact pulses as stress waves to a drilling tool connectable to the shank adapter;
a rotation device arranged for turning the shank adapter around a longitudinal axis;
at least one bearing element arranged for supporting the shank adapter;
a flushing head at a front end of the body, wherein the flushing head includes a flushing element surrounding the shank adapter and configured to form an annular flushing space for feeding flushing agent through the shank adapter to the drilling tool, wherein the bearing element and the flushing element both have split structures including at least two compatible components, and wherein the shank adapter comprises:
a coupling head arranged for connecting the drilling tool;
a rotation portion located at an opposite end portion of the shank adapter relative to the coupling head, the rotation portion including several splines for transmitting torque;
a flushing portion located between the coupling head and the rotation portion, the flushing portion including a transverse flushing opening in contact with an axial flushing portion extending to a distal end of the shank adapter at a coupling head side end, wherein outer diameters of the coupling head and the rotation portion are both greater than outer diameters of the shank adapter located between the coupling head and the rotation portion; and
a bearing portion disposed between the coupling head and the rotation portion, and the outer diameters of the coupling head and the rotation portion both being greater than outer diameters of the flushing portion and the bearing portion.
2. The rock drilling machine as claimed in claim 1 , wherein a smallest diameter of the two outer diameters of the coupling head and the rotation portion is at least 5% greater than the greatest outer diameter between the coupling head and the rotation portion.
3. The rock drilling machine as claimed in claim 1 , wherein a smallest diameter of the two outer diameters of the coupling head and the rotation portion is at least 4 mm greater than the greatest outer diameter between the coupling head and the rotation portion.
4. The rock drilling machine as claimed in claim 1 , wherein the coupling head includes a shoulder provided with an axial contact surface and a protruding axial part provided with a coupling thread, and wherein an outer diameter of the shoulder is greater than the diameter of the coupling head.
5. A method of mounting a shank adapter of a rock drilling machine inside a slide bearing element, the method comprising:
providing a rock drilling machine according to claim 1 ;
implementing a split bearing element including at least two connectable bearing components;
connecting the shank adapter and the split bearing element together by means of transverse relative movement between the shank adapter and the bearing components; and
pre-assembling the bearing element around the shank adapter and mounting a combination of the shank adapter and the bearing element in one piece inside the rock drilling machine.