Workshop and Production Section AIRCRAFT ENGINEERING October, 1944 H E "Benfold", which ha s been produce d b y Th e an d ribs for floats—in fact, all such item s of constant Details and Capacity Faire y Aviation Co., of Hayes, Middlesex, is width which u p t o now hav e been either drawn and the n formed by hand, or press folded. The edges of Th e rang e of material s tha t th e Benfold ca n handle basically a machin e whic h produce s curve d drawn component s produced on this machine are com is practically unlimited, though t o accommodate th e sections. Members so produced may be used in pletel y free from wrinkles. deepes t and heaviest gauges th e machine will ob mai n component assemblies without further mani viously need to be of larger size an d greater power pulation . Where previously the draw-bench was tha n one required for a lighter range of materials used to make a straight length of section and Working Principle Th e machine illustrated is of f h.p. I t comfortably followed up by hand or press forming to obtain Th e Benfold process can be applied in tw o ways. th e required profile, these operations are now com handle s those sections shown and similar sections I n one it combines a draw bench action with a bined in one. A member produced in this way may u p t o 16 gauge. Power is obtained from an electric bending process by means of passing the straight hav e a profile of either a constant or varying radius: moto r which is transmitte d b y mean s of a belt drive ra w material strip through forming dies in conjunc typica l components which can be manufactured are through ' a variable gear and final chain drive and tion with a master former ba r or bars . Th e dies plus clutch.(whic h ma y be of either th e positive dog or mai n rib booms, nose rib booms; fore and aft wing th e section of th e former ba r determine th e resultant friction type) t o th e sprocket. A simple han d clutch stiffeners, bulkhead flanges, formers for monocoques section of the material, while the set of the bar lever is located at the top of th e machine on the determine s th e bend or profile of th e member as a right hand side. A hand wheel controls th e variabe whole. In its other application the raw material gea r and thus the speed of rotation of the driver stri p is routed out t o the required plan contour and sprocket; while a similar wheel is available for hand passed through the machine in th e curved state in turnin g th e driver when th e clutch is ou t and the conjunction with a master former bar. work is being inserted into the machine. While the Th e dies, instead of being rigidly held, are linked machin e can be managed satisfactorily by one togethe r flexibly so tha t the y automatically conform operator , a larger volume of work per hour is ob squarel y t o th e trac k of th e ba r a s i t passes through taine d by employing two operators working- them . together ; in this way, an d using tw o sets of former Drive bars , one operator prepares th e next job while th3 Th e former bar to which is clipped the raw othe r is passing th e first one through the machine. materia l is forced through the dies by a driver A continuous feed is thu s possible. sprocket the teeth of which engage in holes spaced along th e lengt h of th e bar. Figs. 1-3 show a typical frame member entering (top), and almost through the machine (bottom), passing from right to left. Freely sliding clamps on th e entering side locate th e material centrally about th e former bars. Application Th e principle of th e Benfold can b e applied either horizontally—as shown in th e previous photographs —o r in a vertical plane as shown in Fig. 4. Here a different working head is employed, the dies being linked to swing up and down instead of laterally. Thi s arrangement permits of a closer approach to th e machine by the operator, and is more suitable from a drive point of view and disposition of the dies whe n producing certain sections an d formations. I n thi s case i t will b e observe d tha t a double driver sprocket is used. The member being formed from straigh t flat strip is a typical nosing stiffener. Working Heads Th e horizontal head is fitted with a single driver sprocket, while tha t for vertical working carries a double driver. Th e sprockets run freely on th e shaft, being driven b y dogs an d spaced with driving collars t o suit width of track required. An alternative arrangemen t provides for a splined driving shaft carrying splined spacers and sprockets, the latter being held in the nominal position by coil spring washer s at each end. This allows the sprocket to self-align with holes in a curved former fed through in the horizontal position, and avoids the need of fitting spacers to exact length when former is fed in a vertical position. Dies on the horizontal head ar e linked together universally, permitting an amoun t of vertical movement as well as full lateral swing. Those on the vertical head are carried on tw o thin steel strips which permit full deflection as required by the former bar. Centrally below the drive r there is located a roller with quick vertical adjustment , which bears up against the underside of th e former bar, keeping it snug u p t o th e driver. duall y sponsored scholarship schemes for the promotio n of apprentices giving evidence of a ben t for aviatio n progress. Aircraft Apprentices' Scholarships Unde r this fresh scheme, Blackburn appren tice s wil l b e launche d o n th e cours e for a diploma i n Aeronautics a t University College, Hull . Th e firs t awar d will b e mad e this yea r o n th e results URTHE R evidence of th e attentio n which ha s had in being for man y years a scheme for of examination s alread y held. th e British aircraft industry is paying to th e encouragement of boys whose parents are th e technical training and education of i n financial circumstances tha t would otherwise yout h is available in the announcement that deba r the m from following their chosen career. Lewis & Tylor Ltd. Mr . Rober t Blackburn, Chairman of Blackburn Detail s of the de Havilland comprehensive Aircraf t Ltd. , ha s no w mad e availabl e a n annua l educationa l scheme for youth aeronautical I t is muc h regretted tha t on Advertisement scholarshi p of £100 to the apprentice who trainin g are given o n page s 301 an d 305; while Pag e xxxi x of th e Jul y issue th e name of the achieve s th e bes t results i n th e examination s for Westlan d Aircraft have a schem e leading ulti abov e firm appeared wrongly as Lewis;& th e Ordinary Nationa l Certificate i n Mechanical matel y t o a Universit y course a t Cambridg e wit h Taylo r Ltd . The y are , however, so well known Engineering . assistanc e of th e orde r of £250 a year . Nearl y all a s maker s of "Gripolastic " endless belt s tha t it Th e Society of British Aircraft Constructors th e leading British aircraft firms have indivi- i s hope d n o confusion wa s cause d b y th e mistake .
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Oct 1, 1944
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