Electric heating – Metal heating – For bonding with pressure
Patent
1997-02-14
1998-06-30
Berhane, Adolf
Electric heating
Metal heating
For bonding with pressure
B23K 1100
Patent
active
057737835
DESCRIPTION:
BRIEF SUMMARY
This invention relates to double skin composite structures which comprise a layer of a filler material (usually a cementitious material such as concrete) faced with plates (usually carbon steel) and methods of producing the same. A lighter filler material such as filled synthetic resin may be employed for certain applications. More especially, but not exclusively, the invention concerns the production of double skin composite panels which can be assembled to produce double skin composite structures, each panel comprising two steel facing plates positioned one on each side of a layer of concrete and connected thereto by cross members which extend generally normal to the facing plates and are attached at their ends to both facing plates.
Double skin composite structures exhibit similar characteristics to those of reinforced concrete structures and are advantageous in that the steel facing plates act as reinforcements to enable the required strength characteristics to be achieved with structures of overall depth less than those of reinforced concrete. High reinforcement ratios are possible and the steel plates act as permanent shuttering for the central concrete layer.
It has been established that the attachment of the steel facing plates to the concrete must be adequate to ensure that shear forces are effectively transferred and for this purpose it has previously been proposed to employ cross members in the form of steel webs which span and are welded to the inner faces of the steel plates and/or shear studs which are welded to the inner face of one steel plate and are embedded within the concrete of the structure. Such structures are disclosed in GB-A-2136032, GB-A-2136033 and GB-A-2258669.
Applicants have established that the spacing and number of cross members in double skin composite structures is important inter alia to avoid unwanted structural changes during concrete pouring and to prevent buckling of the steel plates away from the intervening concrete during use. The consequent need to employ a large number of cross members in a multiplicity of spaced rows means that welding is both difficult and expensive to achieve particularly when the spacing between the plates is small, that is to say between 30mm and 800mm. Also, any method of construction which generates a significant heat output can result in distortion of the assembled panel which may create problems during later assembly.
To minimise the cost of composite structures, it is necessary to make the individual facing plates as large in area as possible, thus minimising welding around the edges but increasing problems associated with welding individual cross-members to the internal surfaces of the panels.
U.S. Pat. No. 3,676,631 discloses a resistance welding machine for welding transverse rungs between longitudinal rods to form steel reinforcement. Whereas such a machine would be adequate where a single row of cross members is required on narrow plates, it could not operate to position and weld a multiplicity of cross members in spaced rows to facing plates of a double skin composite structure.
The present invention sets out to provide methods of producing double skin composite panels as discussed above and double skin composite panels produced thereby.
According to the present invention in one aspect there is provided a method of sequentially welding a plurality of metallic cross-members in spaced rows to facing plates of a double skin composite panel with the longitudinal axis of each cross-member aligned substantially normal to the facing plates, the method including the steps of causing the facing plates to separate, positioning each cross-member in turn between the facing plates, applying a controlled clamping force to the inner and outer surfaces of each facing plate thereby to hold each facing plate substantially normal to the longitudinal axis of each cross-member and to place the inner surface of each facing plate in intimate contact with the respective end of a cross-member to be welded thereto, subjecting the interfaces between the en
REFERENCES:
patent: 4614013 (1986-09-01), Stevenson
patent: 4724293 (1988-02-01), Bertels
patent: 5398470 (1995-03-01), Ritter et al.
patent: 5624622 (1997-04-01), Boyce et al.
Berhane Adolf
British Steel PLC
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