Tool driving or impacting – Processes
Reexamination Certificate
1998-09-04
2001-02-13
Vo, Peter (Department: 3721)
Tool driving or impacting
Processes
C173S090000, C173S162100, C173S210000
Reexamination Certificate
active
06186246
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for adjusting drilling of a drilling machine in a drilling machine comprising a frame, a percussion piston arranged to the frame and moving in the longitudinal direction of the frame, an absorber situated in the front end of the travel of the piston portion of the percussion piston, a shank situated in the axial extension of the percussion piston and at least two pistons arranged to the frame moveable in its axial direction, the pistons being situated in axial cylinder spaces formed around the shank and arranged to act on the shank and push it towards the front portion of the drilling machine by means of a pressure medium acting on the rear surface of the pistons, whereby at least during drilling such a pressure of pressure medium is set to act on the rear surface of the pistons that the total force of all the pistons acting on the shank and pushing it forwards exceeds feed force acting on the drilling machine during drilling, wherefore some of the pistons are pushed to the foremost position of their travel by means of the pressure medium, whereby the shank is at its optimal percussion point when being supported by them.
The present invention also relates to a drilling machine which drilling machine comprises a frame, a percussion piston arranged to the frame and moving in the longitudinal direction of the frame, an absorber situated in the front end of the travel of the piston portion of the percussion piston, a shank situated in the axial extension of the percussion piston, and an axial bearing arranged to the frame for receiving axial forces directed to the frame via the shank, which axial bearing is formed of at least two pistons which are placed in the frame into axial cylinder spaces formed around the shank and arranged to act on the shank and push it towards the front portion of the drilling machine by means of a pressure medium acting on the rear surface of the pistons, whereby at least during drilling such a pressure of pressure medium is set to act on the rear surface of the pistons that the total force of all the pistons acting on the shank and pushing it forwards exceeds the feed force acting on the drilling machine during drilling and whereby the travel of some of the pistons towards the front portion of the drilling machine is restricted in such a manner that when said pistons are in their foremost position, the shank is essentially situated at its optimal percussion point when being supported by them.
When drilling holes with a rock drill, drilling conditions vary in various ways and in some situations it is necessary to be able to adjust fast and effectively the percussion power of the rock drill or other factors having an effect on drilling. In prior art solutions, percussion power is adjusted by adjusting the pressure of the pressure fluid in the percussion machinery, which is, however, quite difficult to realize accurately and in a controlled manner. Further, in prior art solutions, the position of the shank with respect to the percussion piston is always to be kept at a certain so-called optimal percussion point where as great a portion of percussion power as possible moves to the shank and via the shank through the drill rod to the drill bit. Finnish Patent 84,701 discloses a solution where the position of the shank is set by using several pistons, the pressure acting on which together pushes the shank into an optimal percussion point, but allows it to move backwards by means of a strong return pulse and to receive thus the stress created. In said Finnish Patent some of the pistons can also move farther than the others towards the front end of the drilling machine and thus follow that shank, whereby they receive the return movement and absorb it at an earlier stage during the return pulse.
SUMMARY OF THE INVENTION
In prior art solutions, the adjustment of drilling is difficult and the object of this invention is to provide a method and drilling machine where drilling can be easily adjusted as desired. The method according to the invention is characterized in that the pressure acting on at least some of the pistons is adjusted for providing a desired drilling situation.
The drilling machine according to the invention is characterized in that it comprises at least two pistons, pressure channels separate from one another leading to the pressure spaces behind the pistons and means for feeding pressure fluid to the pressure spaces behind the pistons in such a manner that a pressure is acting on them irrespective of one another.
The essential idea of the invention is that drilling is adjusted by adjusting the position of the shank with respect to the optimal percussion point and the force on the shank when it deviates from its optimal percussion point. In that case, in the adjustment of the percussion power, a desired amount of power is transferred via the shank to the drill rod and the remaining portion of the power is absorbed by the absorber in the front end of the travel of the percussion piston. Similarly, when rock contact of a drill bit is to be adjusted, the pressure acting behind the pistons is kept such that a smaller pressure than feed force is behind the pistons which are capable of moving forwards from their optimal percussion point, the pressure being variable according to the number of drill rods used in long hole drilling in such a manner that at the arrival of a percussion pulse, the drill bit can always be kept as desired in contact with the rock to be drilled without any essential power loss to the absorber. The method can be realized most simply by using several pistons with different travel, the travel of the pistons to the front end of the drilling machine being appropriately restricted. In that case, when feeding a pressure fluid of a suitable pressure behind pistons with different travel, the shank can be moved forwards as desired. An advantage of the invention is that by using pistons moveable to different travel, the shank can be moved mechanically into a desired percussion point that is either the optimal percussion point or one deviating from it. Because the position of the percussion point is precisely determined for all situations, power transfer and thus the percussion power of the machine can be calculated accurately and dimension it according to desired properties during manufacturing. The adjustment of drilling is fast and simple as it can be realized only by adjusting the pressure of pressure fluid acting on the pistons that support the shank.
REFERENCES:
patent: 1715359 (1929-06-01), Hansen
patent: 4366868 (1983-01-01), Salmi
patent: 4624325 (1986-11-01), Steiner
patent: 4934465 (1990-06-01), Salmi et al.
patent: 4993504 (1991-02-01), Rodert et al.
patent: 5351763 (1994-10-01), Muuttonen
patent: 5520254 (1996-05-01), Weber
patent: 2221418 (1990-02-01), None
patent: 9112934 (1991-09-01), None
Helin Aimo
Kiikka Timo
Maki Jorma
Muuttonen Timo
Salminen Pekka
Calve Jim
Ladas and Parry
Tamrock Oy
Vo Peter
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