Patent GB-936834-A (GB)
Title: Improvements in or relating to honeycomb girders
IPC: B23K31/02
Filed: 1960-05-03
Abstract: 936,834. Making girders; angular bending; welding by fusion. F. LITZKA. May 3, 1960 [May 13, 1959], No. 15643/60. Classes 83 (2) and 83 (4). A honeycomb girder comprises a pair of girder sections joined by welding together the teeth of toothed web portions either directly or through web plates or bracing members. Such a girder is made by dividing a solid web girder 1, Fig. 1, along a line 2 of toothed configuration, moving one part 3a longitudinally relative to the other part 3b by a distance equal to approximately half a tooth length and then welding the web projections together as in Fig. 3. Wider or curved or tapering girders may be produced by welding web plates 6, Fig. 10, between the separated parts 3a, 3b of the divided girder. The girders may be braced by elements such as 133a-133g shown in Fig. 22. In a simple form of apparatus, a member of solid web girders 1 and distance pieces 17, Fig. 33, are clamped together on top of a trestle 9 between a stop 10 and screw 11 and the webs are simultaneously severed by a number of cutting heads 14. The cut girders may be moved from the trestle by a wheeled bogy 24 with a lifting device 25 carrying a supporting cross-member 28, 29, Fig. 36. Means for welding the webs of girder parts 3a, 3b comprises channel members 35 and clamps 36, Fig. 38, for holding the parts, a supporting strip of non-weldable material 20 and a welding head 38 on a carriage movable along the girder flanges by wheels 37. Alternatively, the head may be fixed and the work clamped to a movable table. Before welding, the girder parts may be guided and conveyed by pairs of bevelled rollers 45, 46 and outer plain rollers 62<SP>1</SP>, Fig. 41. One section 3a may be moved longitudinally relatively to the other section 3b by separately driving the two pairs of rollers 45, 46. The lifting device of Fig. 36 may be moved on rails 57 up to a series of trestles 55 carrying a roller runway 56 by means of which the girders are moved into the conveying rollers 45, 46 of the welding apparatus of Fig. 43, in which the welding head is not shown. Rollers 45, 46 are mounted in supports 60 between which are bridges 61 carrying guide rollers 62, 62<SP>1</SP>, the former being tapered to engage the inside surfaces of the flanges. The supports 60 are adjustable longitudinally of the girders and the centre support is preferably adjustable at right angles so that curved girders can be produced if desired. Where web plates 6 are to be inserted, they are held in position by comb-like clamping means 79, 80, Fig. 48, before welding. During welding, water-cooled copper blocks 20, Fig. 46, are pressed against the underside of the webs. The welding device 38, Fig. 52, is mounted on rollers 37 running on a girder 85 rigidly connected to a transverse rail 83 mounted on the support 60. When girders having a varying depth of web are to be welded, the rail 83 is laterally adjustable. The device is controlled by a feeler roll 92, Fig. 53 (not shown), engaging the girder. For producing tapered girders two supports 60a and 60b are adjustable relatively to the longitudinal stringers by hydraulic means 99, Fig. 55. A girder with one end splayed out can be produced by bending one girder section 3b about a roller 109<SP>1</SP> by hydraulic devices 106 before inserting the web plates 6a, 6b and 6c. A curved girder is made by first bending the girder sections 3a, 3b between concave and convex dies 113, 114 and a curved row of fixed steps 111 spaced apart to permit the entry of the webs therebetween. Members 117 projecting from the die 114 engage the flange of the girder section 3a during the bending operation. Alternatively, the girder sections may be bent by being slid into pairs of guide rollers 135, Fig. 63, which are then moved into an arcuate position by hydraulic cylinders 136. In another form of bending apparatus, roller pairs 135 are adjusted within radial slots 169<SP>1</SP> so as to lie in an arcuate path and are bridged by members 170 carrying further guide rollers 135<SP>1</SP>. The girder sections 3a, 3b are tack welded at one end 171 and are either pushed through the curved track or are pulled through by a chain 173, entry being facilitated by bending over the outer flange at 172. For welding along a line which is not parallel to the axis of the girder, the welding head is carried by a carriage 121, Fig. 66, transversely movable on a bogie 123 which is movable longitudinally along rails 125. In the case of a girder with inserted web plates, two welding heads may be provided as in Fig. 68, a fixed head 38 for the longitudinal welds and a transversely movable head 38<SP>1</SP> for welds at an angle to the longitudinal axis. The position of the head relatively to the work may be adjusted by means of a feeler roller mounted on the carriage and engaging within the gap between the two girder sections. A milling cutter, sand blast apparatus or a paint spraying device may be associated with the welding head so that the edges may be trued before welding and the welded seam left in a finished, sprayed condition. In order to get good quality welds at the ends of the seam it is recommended that half the welding current and half the feeding rate should be used and the head traversed repeatedly with a circular motion and with a slight lift for each traverse. This movement may be effected by a motor-driven cam mechanism on the carriage. An endless honeycomb girder may be made from strip metal by the apparatus shown in Fig. 76. A web strip 149 is cut at 153 into two halves 3a<SP>1</SP>, 3b<SP>1</SP> and the part 3a<SP>1</SP> is taken round a longer path by rollers 154 in order to bring the projecting teeth opposite each other. The strips 3a<SP>1</SP>, 3b<SP>1</SP> together with flange strips 147, 148 are then passed through a unit 38 where they are welded together from one side, turned through 180 degrees by rollers 155 and welded from the other side by a unit 38<SP>1</SP>. The girders may be cut to length after welding. Columnar girders may be formed by bending individual web sections 5<SP>1</SP> sideways and then welding them to other girders or to plates and the like. Figs. 80 and 81 show examples of such girders. Other examples are described with reference to Figs. 82-89 (not shown).