IMPROVEMENTS IN CASTELLATED BEAMS

Abstract: A method of forming a castellated beam having a series of openings (32) of a first form, e.g. circular, comprises first forming a beam with openings (25) of a second form, e.g. hexagonal. The first form of openings (32) are then cut around the second form of openings (25).

Description: Title - Improvements in Castellated Beams This invention relates to improvements in castellated beams, and in particular to improved processes for the manufacture of such beams Castellated beams are widely used in construction and are generally of I-section, comprising a web of material, most commonly steel, between a pair of flanges. The web of material has a series of regularly spaced apertures, most commonly hexagons or squares. The effect of the apertures is to reduce the weight of a beam of any particular depth, compared to a beam of similar depth having a continuous web. Castellated beams are conventionally manufactured from standard universal beams having a web depth which is less than that of the desired castellated beam. Typically, the web depth of the standard beam is approximately two-thirds that of the castellated beam. A cut is made along the length of the beam, typically using an oxy-acetylene burner. The cut has a regular castellated form, including sections parallel to the flanges on both sides of the centre line of the web. The two sections of the beam are then separated and displaced longitudinally such that the edges of one which are parallel to the flange abut the corresponding edges of the other. The abutting edges are then welded together. The resulting castellated beam has a depth which is greater than that of the original standard beam, typically by 50%, and a correspondingly greater load-bearing capacity, but the weight of the beam is substantially unchanged. The conventional method of forming castellated beams suffers from a number of limitations. First, the range of different shaped apertures which can be produced is small. In practice, only square or hexagonal apertures are used. Also, in order to produce an acceptable weld the abutting edges of the two sections generally require considerable preparation. This is labour-intensive and considerably increases the time and cost of manufacture. There have now been devised improvements to castellated beams which overcome or substantially mitigate these or other disadvantages of the prior art. According to a first aspect of the invention, there is provided a method of forming a castellated beam having a series of openings of a first form, which method comprises separating a beam longitudinally into two halves, displacing said halves laterally and longitudinally and joining said halves when so displaced so as to form a castellated beam having a series of openings of a second form, and subsequently cutting openings of the first form around said openings of the second form. The first form of openings will commonly be circular or oval openings which, due to the absence of corners, provide the best structural performance in the finished castellated beam. The second form of openings may be hexagonal or square openings, as in a conventional castellated beam. Clearly, the longitudinal separation of the beam into two halves will be carried out in a fashion which, when the two halves are displaced and then joined together, leads to the formation of the second form of openings. This can be achieved using the form of cut which is conventionally used to form a castellated beam, as described above. The second form of openings are preferably substantially regular hexagons or squares. It will be appreciated that openings of the first form may be cut around all the openings of the second form, or around only some of the openings of the second form. It will also be appreciated that the openings of the first form may all be the same, or different forms of opening may be cut into the castellated beam. For instance, a regular series of circular openings may be cut, interrupted by one or more elongate openings where required, eg to accommodate ducting or the like. For many applications, the openings of the first form are preferably circular and are formed by cutting around most or all of the second form of openings in the beam. The beam is most commonly a steel beam. The various cutting operations are most commonly performed using conventional cutting apparatus, eg thermal cutting equipment. Examples include one or more oxy-acetylene burners, plasma or laser cutters, any of which may operate under automated control. The joining of the two beam halves to produce the castellated beam will most commonly be carried out by welding, which may be performed using generally conventional equipment. The method of the invention is advantageous primarily in that it permits a castellated beam to be produced with openings of any desired form. Surprisingly, although it involves two manufacturing operations, viz the initial castellation of the beam and subsequent cutting of the openings, the method can be carried out more rapidly and hence more cost effectively than single stage processes for the manufacture of castellated beams with round openings. The method is also flexible, in that openings of a variety of different forms can be produced. The second stage of the manufacturing process, viz the cutting of the openings of the desired first form, also provides the advantage of removing any irregular welding run-off from the ends of the welds by which the two halves of the beam are re-joined, thereby producing openings with clean edges which result in optimal structural performance. Preferably, the longitudinal cut which is made in the beam to divide the beam into halves includes sections which extend parallel to the longitudinal axis of the beam such that such parallel sections of the two beam halves can be welded together. It is particularly preferred that the sections of the cut which define edges of the beam halves which are to be welded together define one or more protrusions from one of the beam halves. When the two beam halves are separated and displaced, and then brought into juxtaposition prior to welding, these protrusions serve to hold the surfaces to be welded together in spaced apart relationship. This greatly facilitates the welding process, and also eliminates the need for extensive preparation of the surfaces which are to be welded together. This in turn greatly speeds up the manufacturing process and hence reduces the labour costs involved. Thus, according to a further aspect of the invention, there is provided a method of forming a castellated beam, which method comprises cutting a beam longitudinally to form two beam halves, each beam half having edge portions which are parallel to the longitudinal axis of said beam half, displacing said beam halves laterally and longitudinally to bring said edges of said beam halves into juxtaposition, and joining together said juxtaposed edges so as to form a castellated beam, wherein at least one of each pair of juxtaposed edges is provided with at least one protrusion which abuts the other of said pair of juxtaposed edges thereby holding said pair of juxtaposed edges in spaced apart relation. Most preferably, protrusions are formed at or near each end of each of the parallel edge portions. The protrusions are preferably generally semicircular in form. Protrusions may be formed on only one of the beam halves, so that the protrusions abut directly the parallel edge of the other beam half. Alternatively, protrusions may be formed on both beam halves, in which case the protrusions on one may abut the protrusions on the other. In any event, where openings, eg circular openings, are subsequently cut in the castellated beam, that cutting operation may remove any residue of the protrusions as well as welding run-off etc as previously described. The invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which Figure 1 is a partial side view of a standard I-section beaming showing a first stage in the formation of a castellated beam; Figure 2 shows a second stage in the formation of a castellated beam; Figure 3 shows a third stage in the formation of a castellated beam; and Figure 4 shows a final stage in the formation of a castellated beam. Referring first to Figure 1, a castellated beam is manufactured from a conventional I-section beam 10. The beam 10 has a depth A and comprises a pair of flanges separated by a continuous web. To convert the beam 10 to a castellated beam, a continuous cut 20 is made along the length of the beam, eg using an oxy-acetylene burner. The cut 20 comprises upper and lower (as viewed in Figure 1) parallel sections 21,22 arranged parallel to the longitudinal axis of the beam 10, on alternate sides ofthe centre line of the beam 10. The ends of successive parallel sections 21,22 are joined by inclined sections 23 ofthe cut 20 which traverse the centre line. The cut 20 has a repeat distance B. To the extent so far described, the cut 20 is similar to the form of cut conventionally used to form a castellated beam with hexagonal openings. However, in this case, the parallel sections 21,22 ofthe cut 20 and the traversing sections 23 are all of approximately equal length so that the openings 25 initially formed in the castellated beam (see Figure 2) are substantially regular hexagons. Also, and particularly importantly, at each end ofthe lower parallel sections 22 the cut 20 defines a generally semicircular protrusion 24. After completion of the cut 20, the two halves 10A,10B of the beam 30 so formed are separated and displaced, first laterally and then longitudinally by a distance corresponding to one-half the repeat distance B ofthe cut 20, into the position shown in Figure 2. Again, to the extent so far described this step of the process is similar to that carried out in the conventional manufacture of a castellated beam. However, in this case, the protrusions 24 on the upper beam half 10A abut the upper parallel sections 21 ofthe lower beam half 10B. The effect ofthe protrusions 24 is to hold the juxtaposed parallel edges ofthe beam halves 10A, 10B in slightly spaced apart relation, thereby greatly facilitating the formation of a weld 26 (see Figure 3) between those two edges. In addition, because the protrusions 24 make substantially only point contact with the upper parallel sections 21 of the lower beam half 10B, any minor imperfections or irregularities in the edges which are to be welded together do not matter. This effectively eliminates any requirement for time-consuming and labour- intensive preparation of the surfaces which are to be welded. This in turn considerably reduces the time required for manufacture ofthe castellated beam, and the associated labour cost. After the two beam halves 10A,10B have been welded together at the juxtaposed parallel edges, the irregular end portions (shown in broken lines in Figure 3) are cut off. The resulting castellated beam has a depth E which is greater than the depth D of the original standard beam 10. In a final step in the manufacturing process, circular openings 32 are cut around the hexagonal openings (see Figure 4). This removes the corners ofthe intermediate hexagonal openings, as well as removing any residue ofthe spacing protrusions 26 and any run-off at the ends ofthe welds 26, thereby producing clean well-defined circular openings 32. The regular circular shape ofthe openings provides the best structural performance. If desired, some or all of the circular openings 32 may be replaced by elongate openings (eg the elongate opening 34 indicated in Figure 4 in broken lines).

Claims: Claims 1. A method of forming a castellated beam having a series of openings of a first form, which method comprises separating a beam longitudinally into two halves, displacing said halves laterally and longitudinally and joining said halves when so displaced so as to form a castellated beam having a series of openings of a second form, and subsequently cutting openings ofthe first form around said openings ofthe second form. 2. A method as claimed in Claim 1, wherein the first form of openings are circular or oval. 3. A method as claimed in Claim 1 or Claim 2, wherein the second form of openings are hexagonal or square. 4. A method as claimed in Claim 3, wherein the second form of openings are substantially regular hexagons. 5. A method as claimed in any preceding claim, wherein the longitudinal cut which is made in the beam to divide the beam into halves includes sections which extend parallel to the longitudinal axis ofthe beam such that such parallel sections ofthe two beam halves can be welded together. 6. A method as claimed in Claim 5, wherein sections ofthe cut which define edges of the beam halves which are to be welded together define one or more protrusions from one ofthe beam halves. 7. A method as claimed in Claim 6, wherein protrusions are formed at or near each end of each ofthe parallel edge portions. 8. A method as claimed in Claim 6 or Claim 7, wherein the protrusions are generally semicircular in form. 9. A method as claimed in any one of Claims 6 to 8, wherein the protrusions are formed on only one of the beam halves, so that when the halves are separated and displaced the protrusions abut directly the parallel edge ofthe other beam half. 10. A method as claimed in any one of Claims 6 to 8, wherein the protrusions are formed on both beam halves, so that when the halves are separated and displaced the protrusions on one half abut the protrusions on the other. 11. A method of forming a castellated beam, which method comprises cutting a beam longitudinally to form two beam halves, each beam half having edge portions which are parallel to the longitudinal axis of said beam half, displacing said beam halves laterally and longitudinally to bring said edges of said beam halves into juxtaposition, and joining together said juxtaposed edges so as to form a castellated beam, wherein at least one of each pair of juxtaposed edges is provided with at least one protrusion which abuts the other of said pair of juxtaposed edges thereby holding said pair of juxtaposed edges in spaced apart relation. 12. A method as claimed in Claim 11 , wherein protrusions are formed at or near each end of each of the parallel edge portions. 13. A method as claimed in Claim 11 or Claim 12, wherein the protrusions are generally semicircular in form. 14. A method as claimed in any one of Claims 11 to 13, wherein the protrusions are formed on only one ofthe beam halves, so that when the halves are separated and displaced the protrusions abut directly the parallel edge ofthe other beam half. 15. A method as claimed in any one of Claims 11 to 13, wherein the protrusions are formed on both beam halves, so that when the halves are separated and displaced the protrusions on one half abut the protrusions on the other.

Inventors: SEVERS JOHN, SEVERS, JOHN
Applicants: SEVERFIELD ROWEN PLC, SEVERS JOHN, SEVERFIELD-ROWEN PLC, SEVERS, JOHN
Application year: 2000
Main classification: E04C3
IPC codes: E04C3