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Aids to Engine Production

Aids to Engine Production Workshop and Production Section November, 1932 AIRCRAF T ENGINEERING A Series of Churchill Machines Described The importance of precision grinding machinery th e drive makes possible a range of four work in the development of the modern aero-engine is speeds. The eight speeds for the table traverse obvious. ar e controlled through an independent box. Apar t from the question of economical pro­ Th e crankshaft is secured in throw blocks of duction , the materials that have brought with special design which when assembled on the shaft the m reliability and made possible the high engine ar e mounted on th e workhead and tailstock centres. speeds now in use could never have been employed The pin is supported at two points opposing the had not the grinding machine been available for cuttin g thrust of the grinding wheel by a single thei r machining. It is only by using a precision steady . The shoes of the steady, which form the grindin g machine that it has been possible and supportin g points, can be adjusted whilst th e shaft practicable to reduce tolerances to the stage dic­ is rotating. tate d by the requirements of interchangeable Locatin g plungers carried in brackets mounted manufacture . on the table provide a means of positioning the Since the earlier days of the aeroplane The thro w blocks when setting up. The under side of Churchill Machine Tool Co., Ltd., have made a th e throw blocks are radiused to form the faces in stud y of the requirements of the aero-engine which the locating plungers can engage. designer and by close co-operation have been able Th e wheelhead is of the same design as that t o develop machines which it is believed cover all employed on all th e latest Churchill plain grinding classes of precision grinding in connection with it. machines. It has a large diameter Nitralloy steel While a number of operations can be carried out grinding wheel spindle which runs in finger-adjust­ on machines of standard design, as for example the able bronze bearings lubricated by a constant flow plain grinder and the centreless grinder, for small of filtered oil. The oil is delivered by a pum p which run s submerged in a large capacity oil sum p a t the shafts and components of circular cross section, oute r end of the wheelhead. several single purpose machines have been developed. The final drive to the grinding wheel spindle is Fig . 1 illustrates a heavy internal grinder now by multiple tex ropes running inside the box specially adapted for grinding th e bores of individual section casting which forms the body of the wheel- cylinders. A special feature of this machine is the head . This design ensures the perfectly steady unusually heavy workhead which has been designed runnin g of the grinding wheel which is so necessary to permit the overhang of the cylinder and its in obtaining high quality of finish and maintaining carryin g fixture. The latter is accommodated on accurat e sizing. th e face-plate shown in the illustration. This A special feature of the Churchill cam grinding design of workhead is capable of more satisfactory machin e is tha t the patented mechanism provides results tha n the type where the bearings have t o be uniform angular rotation of the cam being ground. TH E NEW ALTITUD E RECORD mad e of very large dimensions in order t o accom­ I t is a feature which has increased production, and modat e a large diameter spindle or fixture in which a t the same time made possible more accurate Th e Royal Aero Club, on behalf of the Federation the cylinder is housed internally. results . The contour ground is controlled by a Aeronautique Internationale, has now issued an I t will be seen tha t the grinding wheel spindle is maste r cam manufactured on special machines. Official Certificate of Performance in connection of very large proportions, this member being of Anothe r important point in connection with wit h the world's altitude record established on special design employed only on aircraft work. thi s machine is th e final drive t o the work, which, it Septembe r 16, wit h a Bristol Pegasus S.3 engine in a Th e machine has four speeds of automatic will be noted, is by worm and worm wheel. A Vickers Vespa biplane. traverse , and lour speeds of work rotation. Both machine of this type can be employed for engines I t is interesting to note that the Pegasus-Vespa these ranges are controlled through a gear-box. of any number of cylinders simply b y the changing machin e beat the record previously held by Tw o levers give independent control to each range ove r of the master cam. Lieutenan t Soucek, of U.S.A., b y no less tha n 800 It. so that any combination of work and traverse Th e crankshaft grinding machine illustrated in This is the more striking when it is borne in mind speeds can be obtained. Fig . 3 is based on this Company's plain grinding tha t when the record was made in America the Th e machine has the Churchill one lever control machine practice, but has a special design of work- engine was fitted with two superchargers, one being which means that one lever starts and stops all driv e which gives a very smooth vibration. Free tha t ordinarily built into the engine, while the other motions with the exception of the grinding wheel. driv e is employed. The workhead is of the dead- was an entirely extra one arranged to blow air into An automatically-operated wheel guard descends centr e type, the drive to the crankshaft being th e carburettor, and by this scheme the rated int o position to cover the wheel when the table is transmitte d by a driving peg mounted on the face altitud e of the engine was put up to no less than ru n back for mounting or inspection. plate . This face plate rotates on taper roller 24,000 ft. Such an installation cannot fairly be Fig . 2 illustrates the operation of grinding a bearings on th e spindle nose, and is driven by four compared with the Junkers machine fitted with the four-lobe cam for a radial engine. te x ropes accommodated in grooves cut actually Bristol Jupiter Series VII engine, from whom the A small diameter grinding wheel is made neces­ in the face plate and driven by a pulley placed American wrested the height record, or with the sar y by the dimension of the radius a t the root of abov e the face plate and slightly forward of the Pegasus-Vespa, in each of which only the regular th e lobes. vertical centre line. A gear-box incorporated in supercharge r built into the engine was fitted. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Aids to Engine Production

Aircraft Engineering and Aerospace Technology , Volume 4 (11): 1 – Nov 1, 1932

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb029626
Publisher site
See Article on Publisher Site

Abstract

Workshop and Production Section November, 1932 AIRCRAF T ENGINEERING A Series of Churchill Machines Described The importance of precision grinding machinery th e drive makes possible a range of four work in the development of the modern aero-engine is speeds. The eight speeds for the table traverse obvious. ar e controlled through an independent box. Apar t from the question of economical pro­ Th e crankshaft is secured in throw blocks of duction , the materials that have brought with special design which when assembled on the shaft the m reliability and made possible the high engine ar e mounted on th e workhead and tailstock centres. speeds now in use could never have been employed The pin is supported at two points opposing the had not the grinding machine been available for cuttin g thrust of the grinding wheel by a single thei r machining. It is only by using a precision steady . The shoes of the steady, which form the grindin g machine that it has been possible and supportin g points, can be adjusted whilst th e shaft practicable to reduce tolerances to the stage dic­ is rotating. tate d by the requirements of interchangeable Locatin g plungers carried in brackets mounted manufacture . on the table provide a means of positioning the Since the earlier days of the aeroplane The thro w blocks when setting up. The under side of Churchill Machine Tool Co., Ltd., have made a th e throw blocks are radiused to form the faces in stud y of the requirements of the aero-engine which the locating plungers can engage. designer and by close co-operation have been able Th e wheelhead is of the same design as that t o develop machines which it is believed cover all employed on all th e latest Churchill plain grinding classes of precision grinding in connection with it. machines. It has a large diameter Nitralloy steel While a number of operations can be carried out grinding wheel spindle which runs in finger-adjust­ on machines of standard design, as for example the able bronze bearings lubricated by a constant flow plain grinder and the centreless grinder, for small of filtered oil. The oil is delivered by a pum p which run s submerged in a large capacity oil sum p a t the shafts and components of circular cross section, oute r end of the wheelhead. several single purpose machines have been developed. The final drive to the grinding wheel spindle is Fig . 1 illustrates a heavy internal grinder now by multiple tex ropes running inside the box specially adapted for grinding th e bores of individual section casting which forms the body of the wheel- cylinders. A special feature of this machine is the head . This design ensures the perfectly steady unusually heavy workhead which has been designed runnin g of the grinding wheel which is so necessary to permit the overhang of the cylinder and its in obtaining high quality of finish and maintaining carryin g fixture. The latter is accommodated on accurat e sizing. th e face-plate shown in the illustration. This A special feature of the Churchill cam grinding design of workhead is capable of more satisfactory machin e is tha t the patented mechanism provides results tha n the type where the bearings have t o be uniform angular rotation of the cam being ground. TH E NEW ALTITUD E RECORD mad e of very large dimensions in order t o accom­ I t is a feature which has increased production, and modat e a large diameter spindle or fixture in which a t the same time made possible more accurate Th e Royal Aero Club, on behalf of the Federation the cylinder is housed internally. results . The contour ground is controlled by a Aeronautique Internationale, has now issued an I t will be seen tha t the grinding wheel spindle is maste r cam manufactured on special machines. Official Certificate of Performance in connection of very large proportions, this member being of Anothe r important point in connection with wit h the world's altitude record established on special design employed only on aircraft work. thi s machine is th e final drive t o the work, which, it Septembe r 16, wit h a Bristol Pegasus S.3 engine in a Th e machine has four speeds of automatic will be noted, is by worm and worm wheel. A Vickers Vespa biplane. traverse , and lour speeds of work rotation. Both machine of this type can be employed for engines I t is interesting to note that the Pegasus-Vespa these ranges are controlled through a gear-box. of any number of cylinders simply b y the changing machin e beat the record previously held by Tw o levers give independent control to each range ove r of the master cam. Lieutenan t Soucek, of U.S.A., b y no less tha n 800 It. so that any combination of work and traverse Th e crankshaft grinding machine illustrated in This is the more striking when it is borne in mind speeds can be obtained. Fig . 3 is based on this Company's plain grinding tha t when the record was made in America the Th e machine has the Churchill one lever control machine practice, but has a special design of work- engine was fitted with two superchargers, one being which means that one lever starts and stops all driv e which gives a very smooth vibration. Free tha t ordinarily built into the engine, while the other motions with the exception of the grinding wheel. driv e is employed. The workhead is of the dead- was an entirely extra one arranged to blow air into An automatically-operated wheel guard descends centr e type, the drive to the crankshaft being th e carburettor, and by this scheme the rated int o position to cover the wheel when the table is transmitte d by a driving peg mounted on the face altitud e of the engine was put up to no less than ru n back for mounting or inspection. plate . This face plate rotates on taper roller 24,000 ft. Such an installation cannot fairly be Fig . 2 illustrates the operation of grinding a bearings on th e spindle nose, and is driven by four compared with the Junkers machine fitted with the four-lobe cam for a radial engine. te x ropes accommodated in grooves cut actually Bristol Jupiter Series VII engine, from whom the A small diameter grinding wheel is made neces­ in the face plate and driven by a pulley placed American wrested the height record, or with the sar y by the dimension of the radius a t the root of abov e the face plate and slightly forward of the Pegasus-Vespa, in each of which only the regular th e lobes. vertical centre line. A gear-box incorporated in supercharge r built into the engine was fitted.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Nov 1, 1932

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