Patent GB-553641-A (GB)
Title: Improvements in or relating to the construction of welded frames
IPC: B64D27/00
Filed: 1941-12-05
Abstract: 553,641. Uniting by fusion; electric welding. BAILEY, R. W., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. Dec. 5, 1941, No. 15741. [Class 83 (iv)] In making frames or other structures, particularly for engine mountings for aircraft from tubular members or from solid bar members of cylindrical channel, H-section, &c. formed of a metal liable to have its physical properties impaired by welding such as high tensile chromiummolybdenum or manganese molybdenum steel, the members being joined together by welding either directly or through separate jointing members, each bar &c. member has previously metallicarc welded thereto a ferrule or like formed of a metal whose physical properties are unimpaired by electric welding such as low carbon or mild steel, and the ferrule is then welded by the metallic arc or slow or flash butt welding processes to a similarly ferruled bar &c. member or to a jointing member formed of a similar metal to that of the ferrule. Cracking of the bar &c. members is thus avoided. The ferrule may be external or internal. A plain overlapping ferrule 2 of mild steel &c. is circumferentially arc-welded at 3 and 4 to the member 1, the ferrule being provided with a collar 2a whereby after its attachment to the member 1 a proof loading test for strength may be applied, the collar being machined off when the end 2b of the ferrule is being prepared for attachment to another ferruled member. In welding the ferrule to the member the parts may be assembled and secured in a rotating chuck A and welding effected by stationary or automatically fed electrodes C, D, which may be of mild steel and may be flux coated. The work may be traversed during welding to effect a wavy or scalloped weld. The slag is removed by tapping or brushing. The parts may be heated by a burner E before or during welding and also after welding in the latter case for the purpose of relieving stresses. The ferrule may alternatively or in addition be welded to the member along the edges of holes in the ferrule. The ferruled members may be welded to each other or to the jointing members in situ. In flash welding the ferruled members 1 to the parts 5a, 5b of a jointing member 5, instead of as shown in Fig. 4 by arc welding, the parts are secured by clamps making contact therewith over a length of not less than ¢ in. and the distance between the clamps being about ¥ in. In welding a member 1 to the side of a member 20, Fig. 8, a ferrule 2 arc-welded to the member 1 is welded at 26 to a T-piece 15 itself welded at 27 to a ferrule 21 arc-welded to the member 20 at 23 and 24. The ferrule may be formed with the portion 2d, Fig. 6, of thickness equal to that of the part 5a of the jointing member and 2¢ times that of the member 1 and a part 2c at least 1.5 times the thickness of the member 1 so that this part can carry at least the load which can be transmitted from the member by the welds 3, 4. The joint 6 may be supported during welding by a sleeve 7 which may be removed or retained after welding. In another form the member 1, Fig. 7, is welded at 3 and 4 to a ferrule 2 having a portion 2c over which is slid the portion 32b of a sleeve 32 the portion 32a of which fits the member 1. Where t is the thickness of the member 1 and x a function of the relative mechanical strengths of the metals of which the parts 1 and 5a are formed, the ferrule can be of thickness as to the portion 2c, the portion 32b of the sleeve being equal in thickness to the part 2c. These parts may be machined after the sleeve and ferrule have been welded on the member 1. Several sleeves may be applied, if desired, to build up a composite joint for transmitting heavy loads. In another form a channel shaped ferrule 200 may be welded at 203, 204 on the end of a channel bar 100.