Arrangement and method for controlling drilling parameters
The present invention relates to a method and an arrangement for controlling drilling parameters when rock drilling. The arrangement is arranged such that a drill tool is connectable to a drilling machine by means of one or more drill string components, wherein the arrangement comprises means for rotating the drill tool during rock drilling and for providing a tightening torque for tightening joints between one or more from the group: drill tool, one or more drill string components and drilling machine. The arrangement is arranged to control the rotational speed of the drill tool based on available tightening torque.
1. Arrangement for controlling drilling parameters during rock drilling, wherein the arrangement is arranged such that a drill tool is connectable to a drilling machine by means of one or more drill string components, wherein the arrangement comprises means for rotating the drill tool during drilling and for providing a tightening torque for tightening joints between one or more from the group: drill tool, one or more drill string components and drilling machine, characterised in that the arrangement is arranged to control the rotational speed of the drill tool based on available tightening torque.
2. Arrangement according to claim 1 , characterised in that said means consists of a rotation motor.
3. Arrangement according to claim 2 , characterised in that it is arranged to obtain the available rotational torque as a function of rotation pressure.
4. Arrangement according to claim 3 , characterised in that it further is arranged to:
continuously or at certain intervals obtain the rotation pressure by sensing, monitoring, measuring or calculating, and
compare the obtained rotation pressure with the rotational speed of the drilling machine, and decrease the rotational speed of the drill tool if the current pressure is lower than the required pressure.
5. Arrangement according to claim 4 , characterised in that it further is arranged to perform the comparison using a relation between the required rotation pressure and the rotational speed of the drill tool or by a table look-up, said table comprising a relation between required rotation pressure and the rotational speed of the drill tool.
6. The arrangement according to claim 5 , wherein said relation is a mathematic relation.
7. Method for controlling drilling parameters during rock drilling, wherein a drill tool is connectable to a drilling machine by means of one or more drill string components, wherein the drill tool is rotated during drilling and a tightening torque is provided for tightening joints between one or more from the group: drill tool, one or more drill string components and drilling machine, characterised in the step of controlling the rotational speed of the drill tool based on available tightening torque.
8. Method according to claim 7 , characterised in that the available rotational torque is obtained as a function of rotation pressure.
9. Method according to claim 8 , characterised in the further steps of:
continuously or at certain intervals obtaining the rotation pressure by sensing, monitoring, measuring or calculating, and:
comparing the obtained rotation pressure with the rotation pressure that is required at the current rotational speed of the drilling machine, and decreasing the rotational speed of the drill tool if the current pressure is lower than the required pressure.
10. Method according to claim 9 , characterised in the step of performing the comparison using a relation between the required rotation pressure and the rotational speed of the drill tool or by look-up in a table comprising a relation between required rotation pressure and the rotational speed of the drill tool.
11. The method according to claim 10 , wherein said relation is a mathematic relation.