Implements or apparatus for applying pushing or pulling force – Pipe or rod jack – Tie rod tensioner
Patent
1981-02-23
1983-07-05
Watson, Robert C.
Implements or apparatus for applying pushing or pulling force
Pipe or rod jack
Tie rod tensioner
E21B 1900
Patent
active
043914314
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to bolt and flange connections, and more particularly to devices for tightening coarse thread connections of from 30 mm in diameter which can be used in various branches of the industry.
BACKGROUND ART
To date, wide utilization in tightening coarse thread connections have found numerous means and devices ranging from simple wrenches and power drive bolt tightening machines to cranes or derricks.
For tightening a threaded connection use is generally made of prestraining of a threaded piece, such as a stud piece, of the connection by means of a hydraulic jack or by heating thereof with consequent screwing the nuts. However, the above means and machines lack convenience in operation, are cumbersome and require the use of additional equipment to be employed in conjunction with such hydraulic jacks or for preheating of the threaded piece of the connection.
Known in the art are devices for tightening coarse thread connections as exemplified in USSR Inventors' Certificates Nos. 258,157 and 344,980; Cl. B 25 b 29/02, published Nov. 20, 1969 and July 14, 1972 respectively.
Either of the above devices comprises a pressure element adapted to thrust against one of the pieces to be connected, a tension element having a wedge groove accommodating a power wedge intended to act upon the pressure element to produce strain in the threaded piece, such as a fastening bolt or a stud. The power wedge is a one-way action type, that is one working surface thereof is straight or vertical, whereas another one is inclined, the angle of inclination between the surfaces ranging between 1.degree. and 7.degree. depending on the required operational parameters.
The power wedge is essentially of a rectangular cross-section with side or non-working surfaces thereof being straight or vertical. A screw drive is employed to effect displacement of the power wedge along the groove of the tension element, the screw drive being disposed in the tension element. The tension element is made integral with a head of the fastening bolt. In order to form the wedge groove, wherein the power wedge moves, the pressure element is provided with an inclined surface and accommodated in the groove of the tension element, the inclined surface of the power wedge cooperating with the inclined surface of the pressure element.
The aforedescribed devices afford to produce, at high torques exerted to the nut of the fastening bolt and therefore at high axial loads, the same value of the axial load with dozens of times lesser torques applied, which is to some extent advantageous in operation. However, these devices can only be used as stationary devices, that is they must be provided at every fastening bolt to be tightened. Accordingly, they are preferably to be used in conjunction with flange connections or couplings which are subject to frequent dismantling, such as those dismantled several times within one week.
The use of the above devices for flange connections which are not subject to frequent disassembling is economically unjustified, since each fastening bolt should be provided with such ancillaries as a wedge, screw, pressure element and other extra parts. Also, these devices fail to effect repeated tightening of a threaded connection with a view to attain a rated load to be exerted to a bolt or stud.
Further known is a detachable means for tightening threaded connections which can be removed from one tightened connection to be used for tightening another connection (cf. Patent of Germany, Federal Republic of, No. 2,238,974; Cl. B 25 B 23/14, published Dec. 12, 1974). A pressure element in this device is fashioned as a body embracing both a tension element and a nut of a stud piece to be connected. For imparting tension to the stud piece use is made here of an eccentric shaft acting through a sleeve member on the tension element and exerting pressure against the pressure element through rollers. Also, there is provided a lever or bar secured to a square head at the ends of the eccentric shaft. This device, howev
REFERENCES:
patent: 3285568 (1966-11-01), Biach
patent: 3749362 (1973-07-01), O'Connor
patent: 3774352 (1973-11-01), Weber
patent: 4010669 (1977-03-01), Kloren
patent: 4104934 (1978-08-01), Raschke et al.
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