| 摘要 |
To measure the penetration rate of a drill string, a signal generator includes a friction wheel that can be engaged with the side of a drum upon which is wrapped a cable used to lower the drill string by turning the drum. The friction wheel is mechanically coupled to a cam which operates a pneumatic switch each time the cam rotates to produce depth indicator signals that are transmitted to a recording system, including a moving strip chart record, to record increments of penetration. The signal generator further includes a first pneumatic counter which counts pneumatic pulses from the switch beginning with the first pulse after addition of a segment of pipe to the upper end of the drill string. The first pneumatic counter transmits pneumatic pressure to a pneumatic actuating cylinder to shift the friction wheel radially inwardly of the drum when the number of pulses corresponds to a number of increments of penetration caused by unwrapping the outermost lap of cable from the drum. A second pneumatic counter counts pneumatic pulses from the switch subsequent to such shift and relieves the pressure transmitted to the pneumatic actuating cylinder, so as to return the friction wheel to its initial position, when the total number of pulses counted by both counters corresponds to a number of increments of penetration in the length of one segment of drill pipe making up the drill string.
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