Metal working – Means to assemble or disassemble – Heat exchanger
Patent
1991-05-09
1993-05-11
Cuda, Irene
Metal working
Means to assemble or disassemble
Heat exchanger
254 29R, B66F 108
Patent
active
052089673
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a tube extraction apparatus for tubes and like elongated articles. An example of the application of the invention is to a tube extraction apparatus suitable for removing condenser and heat exchanger tubes from their mountings in electrical power generation stations. The invention has many other applications.
BACKGROUND OF THE INVENTION
Apparatus for extracting tubes from heat exchangers and the like has already been proposed. An example of such an apparatus is disclosed in GB 2,113,598A. However, such an apparatus is of relatively elaborate and complex structure, and this is reflected in the complexity of the mode of operation of the apparatus. Accordingly, improvements are desirable in relation to the simplifying the construction and operation of the apparatus, its cost, its space requirements, particularly axial length, and indeed its reliability. An area in such prior apparatus which particularly calls for improvement concerns the method of gripping the article to be extracted, and the present invention is particularly, though not exclusively, concerned with providing improvements in this respect.
Accordingly, an object of one aspect of the present invention is to provide an extraction apparatus for tubes and like elongated articles providing improvements in relation to one or more of the matters discussed above or generally.
According to a first aspect of the invention there is provided an extraction apparatus for tubes and like elongated articles as defined in claim 1 of the accompanying claims.
A second aspect of the invention concerns the means for applying an extraction load to the article concerned.
Prior proposals in this regard include the use of a collet assembly mounted within the tubular piston rod of the hydraulic ram assembly, whereby an extraction load is transferred radially inwards through a collet head or chuck to the collet jaws, and thus to the article.
While this prior proposal may well operate satisfactorily in laboratory test conditions, it is found that in actual normal use conditions, it is subject to significant problems and shortcomings. These concern not only the size and weight of the apparatus, but also a tendency to cease-up and jam in use, whereby the apparatus becomes unusable, service is imperative, and it is then found that it is extremely difficult to detach the jammed collet assembly for servicing purposes, and later to replace it.
Accordingly, it is an object of this second aspect of the present invention to provide improvements in relation to one or more of the matters discussed and disclosed herein, or generally.
SUMMARY OF THE INVENTION
The present invention relates to apparatus for effecting stepwise, lengthwise movement of elongated articles such as tubes. The apparatus includes gripping means for the article, thrust means for operating the gripping means and applying a load longitudinally of the article, and the gripping means includes a collar to encircle the article and grip it by tilting relative to the longitudinal axis of the article. The thrust means includes a fluid operated motor or hydraulic cylinder. In further accordance with the present invention such an apparatus is adapted for extracting tubes by providing primary and secondary gripping means operable in sequence in order to provide for extraction in one direction of movement and then to provide for a return movement with a holding effect such as will inhibit elastic return movement of the elongated article or tube being extracted. The fluid motor or cylinder is disposed coaxially with respect to the axis of the elongated article or tube, and the primary gripping means applies the extraction load through a series of radially movable jaw elements. The secondary gripping means comprises a collar that is effective to inhibit elastic return movement of the tube between the successive extraction steps carried out by the primary gripping means.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an axial section through extraction apparatus for tubes and like elongated arti
REFERENCES:
patent: 2356899 (1944-08-01), Stutter
patent: 3507028 (1970-04-01), Stellatella
patent: 3791011 (1974-02-01), Keys
patent: 4434969 (1984-03-01), Von Rudin
patent: 4586695 (1986-05-01), Miller
patent: 4679315 (1987-07-01), Overbay
patent: 4959899 (1990-10-01), Martin
Cuda Irene
Wicksteed Engineering Limited
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