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Shandong
Province,
China,
262500
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山东省青州市开发区电商大厦
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disc is not in touch with the tool joint. But the cam (36) with a fixed slope rotates
along with the rotation of the float body, the rollers (35) located at the back of the
jaw will go up along the spiral surface and comes close to the center along the
groove (E-E Turned), and at last grip against the drill string joint. Meanwhile the
notched gear will drive the brake disc, the jaw rack and the laws on the floating
body and drill string' to rotate for the operation of making up and braking out.
The lower tongs is to drive the jaw rack to rotate in the case body through air
gripping cylinder (38), thus gripping or loosening the joint beneath.
3.3.2 The floating body, owing to the relative position between the upper tongs
and the lower tongs is variable; it is necessary that upper tongs can float relatively
to the lower tongs.
3.3.3 The brake mechanism, in order to cause relative motion between roller
and cam (in the operation of making up and braking out), it is necessary to design a
brake mechanism of the law rack for every type of power tongs.
Refer to Fig. 1, the brake mechanism consists of the two brake bands round
the brake discs, connecting rod (28) and adjusting tube (27), the spring force of the
adjusting tube can be adjusted to change the value of braking moments by rotating
the adjusting tube. The brake mechanism can center the floating body with drill pipe
and meet the requirements of eccentric joint.
3.3.4 Restoration mechanism: There are three problems of restorations for
aligning notches to power tongs of open head, that is, the aligning of floating body
with the case body, the aligning of jaws rack of the upper tongs with the floating
body, and the aligning of laws rack of the low tongs with the case body. First, align
approximately with high speed, then align accurately with low speed, by this way,
the floating body can be aligned exactly with the case body.
The aligning of law rack of the upper tongs with the floating body is just the
same as the aligning of jaw rack of the lower tongs with the case body. Refer to B-B
turned of Fig. 1, pin (40) is fixed on the floating body, the locating turning pin (41)
connected with the locating handle (4) is fixed on the sleeve (23) of the brake disc.
Obviously, the floating body in the position as shown in Fig. 1 is capable of
relative motion to the right with respect to the brake disc, that is, to make counter
clockwise rotation (breaking out position). If the locating handle is reversely turned
180 degree, the floating body is capable of relative motion to left with respect to the
brake disc, that is, to make clockwise rotation (making up position). The brake disc
will be aligned with the floating body while the floating body is turned reversely until
the locating pin (40) is in touch with the locating turning pin (41 ) . In order to
observe conveniently, the position of the locating handle of the upper tongs should
