Method and arrangement for controlling rock drilling

Tool driving or impacting – Processes

Reexamination Certificate

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Details

C173S002000, C173S004000, C173S011000, C175S027000

Reexamination Certificate

active

06253860

ABSTRACT:

The invention relates to a method for controlling a rock drilling machine, wherein the drilling is controlled on the basis of a pressure that acts in a pressure conduit of a hydraulically operated rotation motor and that is proportional to the rotation resistance of a drill rod.
The invention further relates to an arrangement for controlling a rock drilling machine, the arrangement comprising means for measuring the pressure acting in a pressure conduit of a hydraulically operated rotation motor and for controlling the operation of the rock drilling machine on the basis of the measured pressure.
When drilling holes with a rock drilling machine, different so-called automated fissure-drilling methods and methods for adjusting the moment of the drilling utilize the pressure acting on the rotation motor of the drill rod. This is based on the idea that the pressure value is proportional to the rotation resistance acting on the drill rod during the drilling and the adjustment can therefore be carried out on the basis of this pressure value. In such methods, for example the rate and direction of the feeding are adjusted on the basis of the pressure value. When adjusting the feeding, the feed force is decreased as the pressure value representing the rotation resistance increases, and correspondingly, the feed force can be increased when the pressure value decreases. Correspondingly, if the rotation resistance increases to a certain level, the feeding is switched to a return motion on the basis of the pressure, so that the drill bit would not get stuck in broken rock or the like.
The adjusting methods implemented in the known manner are problematic in that the changes of pressure resulting from losses occurring in the apparatus itself and from alterations in the viscosity of the pressure fluid cannot be taken into account in any way in the prior arrangements. Also, when the drilling starts and the apparatus is cold, due to the temperature of the pressure fluid the viscosity is different than in an apparatus having a normal temperature, which slows down the drilling inconveniently or causes unnecessary return movements. Further, in long hole drilling as the number of the drill rods increases, the rotation resistance to the drill rod increases and therefore the drilling requires a greater rotation force. The prior arrangements do not take into account this matter either, which results in the occurrence of the above-described problems also during long hole drilling.
The purpose of the present invention is to provide a method and an arrangement which avoid the drawbacks of the prior methods and which provide more accurate and reliable operation of the apparatus. The method according to the invention is characterized in that before the actual drilling, the value of the idle pressure acting in the pressure conduit of the rotation motor is measured when the drill rod is rotated, said value being used as the reference value to control the actual drilling, and that the control value used to control the drilling is the difference between the pressure acting in the pressure conduit of the rotation motor measured during the drilling and said idle pressure.
The arrangement according to the invention is characterized in that it comprises a control unit which measures the value of the actual idle pressure acting in the pressure fluid conduit of the rotation motor when the drill rod is rotated before the actual drilling, and which stores the measured idle pressure value in the memory and measures during the drilling the pressure value acting in the pressure fluid conduit of the rotation motor and controls the rock drilling machine on the basis of the difference between the pressure value measured during the drilling and the idle pressure value stored in the memory.
The basic idea of the invention is that before the actual drilling, the pressure acting on the rotation motor is measured and this measured so-called idle pressure is used as the zero level or reference value during the use of an adjustment method based on the pressure acting on the rotation motor. In such a case, the pressure value on which the actual adjustment is based is the difference between the idle pressure and the pressure measured during the adjustment. This measurement can be carried out both at the beginning of the drilling before the drill bit touches the rock and, correspondingly in long hole drilling, before the feeding and percussion are set to the values according to normal drilling.
The invention has the advantage that the measurement of the idle pressure value carried out at the beginning of the drilling provides at all times a reliable zero level which is proportional to the mode of operation of the apparatus and to which the measurement of the pressure value of the actual drilling method can be compared in a reliable manner. in such a case, both the differences resulting from the temperature of the pressure fluid and the viscosity values, and the other losses occurring in the apparatus are taken into account, and therefore the adjustment can be carried out in a reliable and accurate manner. Also, common malfunctions can be avoided with the method according to the invention. The invention also has the advantage that in long hole drilling the zero level can be the pressure value that acts on the rotation motor and that is produced by the friction between the extension rod and the wall of the drill hole, and the mass of the extension rod, and the normal drilling adjustment is thus based on the difference between the aforementioned pressure value of idle rotation and the actual pressure value. The invention also makes it possible to control better not only normal drilling but special situations occurring in drilling. Such special situations include, for example, through drilling that has previously resulted in a sudden forward movement of the rock drill. In the arrangement and method according to the invention, through drilling is detected immediately when the difference between the aforementioned pressure value of idle rotation and the pressure value of the actual rotation comes rapidly close to zero, whereupon the drilling adjustment reacts in a predetermined manner.
The invention will be described in greater detail in the accompanying drawings.


REFERENCES:
patent: 3550697 (1970-12-01), Hobhouse
patent: 3659655 (1972-05-01), Gyongyosi
patent: 3872932 (1975-03-01), Gosselin
patent: 4165789 (1979-08-01), Rogers
patent: 4356871 (1982-11-01), Fujikawa
patent: 5168937 (1992-12-01), Hamner
patent: 5348106 (1994-09-01), Mattero
patent: 5449047 (1995-09-01), Schivley, Jr.
patent: 5458207 (1995-10-01), Mattero
WPI/Derwent's abstract, No82-99288E, week 8246, Abstract of SU, 898048 (Ivano-Frank Oil Gas), Jan. 15, 1982.

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