Metal working – Plural diverse manufacturing apparatus including means for... – Binding or covering and cutting
Patent
1995-03-11
1998-10-13
Briggs, William R.
Metal working
Plural diverse manufacturing apparatus including means for...
Binding or covering and cutting
29890046, 219107, B23P 2300
Patent
active
058193847
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a plant for producing metal heat exchanger tubes.
2. Description of the Prior Art
Tubes of this type, which have spiral heat exchanger ribs attached to their exterior surface, are also known as ribbed tubes. For use in steam generators, these ribbed tubes are made of boiler steel. The ribs are made from a section of flat steel (sheet strip or drawn section) and are welded to the tube surface continuously or by segment (e.g. EP 0 031 422 B1). The invention refers primarily, but is not exclusively limited, to this type of ribbed-tube production. The invention also includes plants for producing ribbed tubes from other metals, such as copper or aluminum, whereby, furthermore, different materials may be used for the tubes and the ribs, respectively (e.g., aluminum ribs on steel tubes). Furthermore, other types of attachment techniques (e.g., soldering, shrink connection, rolling the rib base into the tube also be used (e.g., DE-OS 23 60 477).
In the plants normally used today to produce ribbed tubes from steel materials, the ribs are joined to the surface of the smooth tubes using the HF-welding technique. The frequency normally used for the welding is in the approximate range of 400-500 kHz. In these plants, each smooth tube supplied via a smooth tube bed must be placed into spiral motion relative to the flat material used to form the ribs, so that the flat material lies closely and in loops that project radially outward around the smooth tube, which has a clean metal surface. This often requires considerable forming work to be carried out, which means that the drive must be equipped with suitably high driving power. In addition, because of the feared notch effect, no striae may be permitted to develop on the tube surface as the result of gripping tools used to produce a spiral motion, particularly in the case of tubes intended for boiler construction.
For these reasons, ribbed-tube production plants today are normally equipped with a rotating chuck, similar to a rotating bench, which securely grasps the smooth tube at one end and can be placed into rotation. In order to produce the spiral movement, a linear movement is superimposed on the rotational motion in the direction of the tube axis (longitudinal axis). For this purpose, the rotating chuck is mounted in a carriage-type holding frame, which can be motively moved on the machine bed. The length of the machine bed corresponds to the maximum tube length to be produced. As a rule, the rotational motion and the linear motion can be steplessly adjusted relative to one another, so that the ribbed tubes can be produced with any desired division (distance between two adjacent ribs). The conveyor mechanism for the flat material (strip conveyor) of the ribs is stationary in the operating state, as is the welding unit with the welding electrodes, while the rotating device (rotating chuck with carriages) moves linearly along with each respective tube. It is also possible to select a kinematically-reversed arrangement, in which the rotating chuck remains stationary while the strip conveyor is mounted on a carriage that can move along the machine bed (e.g., EP 0 259 607 B1 or EP 0 303 074 A2).
Ribbed tubes for steam generators are usually 14-18 m or even 22 m in length. This leads to correspondingly long and heavy machine beds and thus to correspondingly high investment costs for plants of this type.
From U.S. Pat. No. 3,047,712 it is known, for an HF-welding technique for ribbed-tube production, to produce the spiral movement of the tube by means of a group of driven rolls distributed around the tube circumference and set with their rotational axes at a slant to the tube axis. In this case, the slope of the spiral movement depends on the relationship between the roll speed and the slant angle. However, due to the large deformation forces that arise when rib material is wound around the tube, this process has not proved practical, at least when steel materials are used, because the drive fo
REFERENCES:
patent: 3578165 (1971-05-01), Boose
patent: 3652820 (1972-03-01), Boose
patent: 3670945 (1972-06-01), Furstenberger et al.
patent: 4079611 (1978-03-01), Osterkorn et al.
patent: 4259771 (1981-04-01), Ogata
Bruhl Fritz
Rombaut Hendrik
Briggs William R.
Mannesmann Aktiengesellschaft
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