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between the wheels, at which point it is de-energized to release the work. The wheels next advance, grind, Centreless Grinding of reopen, and the piece ejected, the cycle being repeated at any desired rate from 6 to 18 seconds. The current employed for the magnet is A.C. in order to do away with the difficulty of residual magnetism in the piece. Headed Pieces Magazine The magazine from which the work is presented to Monotonous Operation Eliminated and Production the swinging arm may be of various types. FIG. 3 shows a simple form of chute which is employed for Increased by an Automatic Machine the wheel assemblies shown in FIG. 1, the descending column of pieces being retained by a catch, which is depressed by the swinging arm to enable the bottom In FIG. 1 arc illustrated certain headed parts which faithfully reflected in the steadily falling production as piece to be picked up. In other cases, such as valves are required in very large quantities ground on the the day advances as well as in the difficulty in obtain and bolts a rotary table is employed as shown by the shank to an accurate diameter. The closeness of the ing labour to undertake this week after week and photograph FIG. 2, this table being indexed forward limits on such work as valve stems needs no emphasiz month after month. ing, and the limits on the journals of the geared wheel one station each time that the swinging arm picks up It is with the object of reducing such labour assembly shown are equally tight. Even in the case of a piece. difficulties and maintaining a high rate of output that standard bolts, however, manufacturing requirements the new Scrivener magnetic loading device (FIG. 2) call for an ever-increasing accuracy on the shanks, has been evolved. The machine shown embodies three Limits and Production more especially with the growth in the practice of main features (1) the controlled-cycle whereby the No difficulty is presented in maintaining work thread rolling, in which full success is largely depend grinding of a piece is effected without any physical correct to size within 0.0001 in., but the hourly pro ent upon the initial dimensional accuracy of the shank. effort or attention, and which is now so well known duction is affected both by the degree of accuracy that it need not be further described; (2) the magnetic required on the finished piece and the amount of stock For this work, normal hand-operated centreless loading device which picks up the workpiece and lays to be removed. In the case of a piece requiring merely grinding machines have been largely used in the past, it between the wheels; and (3) the form of magazine a small stock removal of (say) 0.004 in. and calling but this machine has presented a difficulty which is employed to keep the loading arm supplied. for no greater accuracy than plus-minus 0.0005 in. a likely to be largely accentuated in the future. This production of 600 pieces per hour could be obtained, difficulty lies in the monotony of the work for the but in this connection it is important to bear in mind operator, who is engaged continuously and without Magnetic Loading Arm that this is a production which is maintained auto relief on picking up a piece, laying it on the work- It will be seen from FIG. 3 that this consists in matically week-in and week-out, maintained more plate of the machine, pulling over the plunge grinding essentials of a swinging arm B incorporating a lever to close the wheels for grinding, and raising over without any physical effort on the part of an magnet, the arm being operated by the small hydraulic this for the opening of the wheels and the ejection of operator, and without any decrease due to fatigue or cylinder C which in turn is linked up with the con- the piece. With a simple and convenient machine, it is ennui due to the monotony of the operation. trolled-cycle mechanism Before the wheels commence possible to obtain quite an interesting production for to close, the arm swings over to the rear, where the Full particulars of this machine and its capabilities the first hour, but it is an operation which is devoid of magnet is energized to pick up the piece, it then can be had from the makers: Arthur Scrivener Ltd., all mental interest, and the monotony of the task is swings forward to lay the piece on the workplate Tyburn Road, Birmingham. 1 in., 2 in. as tabled below. By this means a total adjustment range of 4 in. is afforded, with micrometer Tools for the Workshop control throughout the range. The adjustable member can be quickly removed from its base and it is then, in effect, an adjustable ground thread gauge block which may set to any A Selection of Notes on Recent Equipment and dimension between in. and 1 in. and read off in increments of 0·0005 in. New and Well-Tried Methods and Materials Dimension Table Ground Thread Micrometer Jack creases to a maximum of 5} in. may be obtained by Component Adjustment Range (ins.) attaching the special hardened and ground gauge Micrometer jack only .. 1·750—2·000 There are daily occasions when in the majority of blocks applied in the following widths: ¼ in., ½ in., Jack with gauge blocks jig and tool shops the need is felt for a precision G.B. widths (ins.) levelling device which will afford instant and accurate 0·250 2·000—2·250 adjustment to limits of 0·0005 in. The micrometer 0·500 2·250—2·500 adjustable jack (FIG. 1) has been designed to meet 0·500+0·250 .. 2·500—2·750 such requirements and, by its use, set-up problems can be quickly and efficiently overcome in connexion with 1·000 2·750—3·000 work on irregular shaped castings and similar un 1+0·250 3·000—3·250 evenly constructed components, such as the marking 1+0·500 3·250—3·500 out of crankshafts, etc., and various forms of grinding 1+0·500+0·250 3·500—3·750 and milling operations. The micrometer adjustable 2 3·750—4·000 jack is provided with three interchangeable heads, 2+0·250 4·000-4·250 i.e., flat, vee, and knife edge. 2+0·500 4·250-4·500 2+0·500+0·250 4·500—4·750 The collapsed height with the standard flat head 2+ 1 4·750—5·000 inserted is 1¾ in. ; this height may be increased to 2 in. 2+1+0·25 0 .. 5·000—5·250 by turning the knurled sleeve; this sleeve is provided 2+1+0·50 0 5·250—5·500 with a 50 division scale, each division reading a height 2 + 1+0·500+0·250 .. 5·500—5·750 increase of 0·0005 in. and a complete turn a height increase of 0·025 in.; this will, of course, register with This micrometer adjustable jack is made by Euco the engraved division lines on the inner sleeve, exactly Tools Ltd., 44 London Road, Kingston-upon- as on an ordinary micrometer. Further height in Thames, from whom full particulars can be obtained June 1949 201
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jun 1, 1949
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