quickly and easily obtained and it is claimed that a marked improvement in tool life is achieved. In a recent application drilling a stainless steel billet it was found that the boring operation shown in FIG. 3 was reduced from 4½ hrs. by normal manual A Selection of Equipment of Use in the Production and Maintenance operation to 1¼ hrs. by the use of the apparatus. The of Aircraft, Missiles, Space Vehicles and their Components attachment can be manufactured to suit individual requirements and is easily installed by the works Turbine Blade Production with Hydro-Copier Long life and rigidity is ensured by a massive cast engineer. It is unnecessary for the original tailstock Vero hydraulic copiers in use in the Leavesden baseplate. Hardened and ground worms drive the to be replaced from time to time as this new attach factory of the de Havilland Engine Company reduce tables through aluminium bronze worm wheels split ment is adaptable for all normal operations. This the time taken to machine mild steel turbine blades to provide adjustment for backlash, and immersed in by 40 per cent. an oil bath to prevent wear. A specially designed 16 The Vero hydro-copier is manufactured by Vero gallon capacity hydraulic power pack is driven by a Precision Engineering Ltd., Southampton. It can be 1¼ h.p. 440 v. three phase electric motor. fitted in less than 30 minutes to the worktable of any standard vertical milling or slotting machine to pro Tooling Balls vide the facilities of a profile mill. Accurate positioning and checking of holes located at compound angles or, in two or more planes, in machining and tooling set-ups is greatly simplified by using tooling balls. These consist of a high precision ball electrically welded to a plain or shouldered shank —both parts being made from hardened stainless steel. With the shank inserted into a hole accurate mea surements can be taken from the ball to lines or surfaces in any plane. Two basic types are available, one has a plain shank and is intended to be pressed into a hole or locked by a set-screw. The other is equipped with reference shoulder beneath the ball so that it may be positioned and re-positioned with accuracy. equipment, which is the subject of provisional patent, can be obtained from Speedy & Eynon Ltd., Lion Works, Warstone Lane, Birmingham 18, England. Spherical Grinding Turbine blades for certain types of turbo super Recent developments in the bearing industry neces charger are manufactured at the de Havilland factory sitate in many cases the grinding of spherical outer from square section mild steel bar. Four machining diameters on ball, roller and friction bearings and operations are carried out on each blade. Milling of cages. Although at first sight some of these pieces the inside and outside aerofoil forms is followed by might not be thought suitable for centreless grinding, two machining operations at the blade neck. Each the difficulties which they present have been overcome profile is copied from a flat master template to a by means of special equipment on the No. 2 controlled- production tolerance of 0·004 in. cycle automatic centreless grinder produced by Arthur Alternative production methods for these turbine Scrivener, Ltd., Tyburn Road, Birmingham 24. Pieces blades involved the use of a specialized multi-spindle are loaded into a sloping magazine alongside the profiling machine. The de Havilland Engine Company grinding wheel, and at the commencement of a cycle has experienced difficulty in utilizing the full produc the bottom piece is dropped between two disks at the tion capacity of this expensive machine tool on this end of the push-feed mechanism which then advances task, and the complete machining cycle for a single to place it into position between the wheels of the blade in any event was taking 38 minutes. The use machine. Grinding wheel and control wheel then close of the Vera copier on a standard vertical mill not only for the grinding operation, after which they re-open, released a specialized machine tool for other work, allowing the ground piece to be withdrawn and ejected, but also reduced the cycle time to 23 minutes. the whole operation from first to last being entirely A skilled setter is employed to set up the master automatic. template and blade jig for each production run. As the spherical form of the diameter would prevent Actual machining is carried out by a semi-skilled a piece of this description maintaining a vertical operator. position during the grinding operation, the one end The first of two Vero Hydro-copiers supplied to the of the push-feed mechanism is provided with two de Havilland company has now been in operation for disks of suitable diameter which house and support the piece, but so lightly as not to interfere with its two years. The performance of this machine led to a freedom to rotate when grinding. The exact location repeat order after only three months. Both have been between the wheels on the V-section workplate is in continuous use including night shift work, and show negligible wear. ensured by notches in this supporting plate. The problem of loss of accuracy caused by wear on The radius-truing attachment is located above, and the milling cutter is overcome by the use of a scries brought into action between, the wheels and the latter of tracing styli of different diameters. Blunt cutters can be dressed without in any way breaking down the Each type is available in seven different ball dia are reground to a standard under-size, and used in set-up of the machine. This attachment is hydrauli- meters from 0·250 in. diameter to 1·000 in. diameter, conjunction with the appropriate stylus. cally-operated, adjustable for any location across the cither as individual pieces or in complete sets of seven. The main use of the Vero Hydro-copier at the de face of the wheel, and will cover a range of radii When ordered in sets, the tooling balls are supplied Havilland works has been for the quantity production between J and 3 in. Wheel diameter is 20 in., the in a neat Mahogany case for protection and easy of turbine blades, at a rate of about 50 per day from usual width for the general run of pieces of this storage. These tooling balls are produced by Industrial each machine. The versatility of the machine has, description being 1¼ in. Stock removal is frequently up Tectonics Inc., 3686 Jackson Road, Ann Arbar, however, been exploited in carrying out other copying to 0·013 in., the number of cuts depending naturally Michigan, U.S.A. and are available from Insley work. upon the accuracy and degree of surface finish required, Industrial Ltd., Insley House, 5 Windmill Street, The ability of the copier to produce small runs of but for a 2 in. diameter piece the machine usually London, W.1. complicated profiles direct from a simple metal or operates upon a 15-sccond cycle. perspex master, drastically reduces tooling costs. Hydro-Pneumatic Boring and Drilling Attachment Hand Grinding Tool Copying of a profile direct from a component is possible, due to the 1 to 1 ratio of the hydraulic linkage A new version of the well-tested hand angle grinder Messrs Speedy & Eynon Ltd., Warstone Lane, between master and copy. A simple clamping device type MSF 676 is now available in the United Kingdom Birmingham, have recently developed equipment for enables the Vero copier to be removed from a base from Verrolec Ltd., 721 North Circular Road, fitting to standard centre lathes which enables boring, machine in five minutes. As a result, the copier need Cricklewood, London, N.W.2. drilling and reaming to be carried out quickly and never be out of service due to the necessity for main For grinding down and smoothing welding seams, accurately without operator fatigue or wear to the tenance or repairs to the milling machine. machine itself. and for fettling castings with a flexible roughing wheel, The Vero Hydro-copier will machine external pro The equipment, which takes the place of the normal the 676 is a tool of unusual efficiency. files up to 15 in. diameter and internal profiles up to tailstock, consists of a number of cylinders which are It is versatile, and can be fitted with a range of 9 in. diameter. The stylus is provided with 3 in. connected to a compressed air supply. These pneu accessories for such specific jobs as removal of risers longitudinal and 4 in. vertical adjustment. Cutting matic cylinders feed the drill, reamer or boring bar at and casting funnels; polishing over straight or curved speed is variable between 2 and 10 in./min. and more constant speed into the piece to be machined. The sheet metal, with a rotary rubber disk and abrasive than 2 cu. in. of mild steel can be removed in one entire operation is controlled by the throwing of an fibre wheel. minute. An overall copying accuracy to within 0·0005 electric switch. A single-phase a.c. and d.c. motor is fitted, having of template can be achieved. In order to prevent undue pressure being brought a normal rating of 1·25 h.p., air-cooled and radio Simplicity of setting-up is attained by maintaining upon the tool, a hydraulic control cylinder is incor screened. According to type, the motor can be geared accurate relationship between the template and cutting porated in the apparatus. The unit is fitted with a from 4,300 to 8,400 r.p.m., depending on the require tables. Each table is provided with a central location quick return system for the tool withdrawal. As the ments for the particular job. The tool weighs from and accurately aligned central tenon groove. speed is infinitely variable, suitable feed rates are 12·2 to 15·2 lb., again according to type. July 1962 213
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jul 1, 1962
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