pins, so that the movement of levers causes them to grip the board
for the lift, or release it for the fall, these levers being under the
control of the attendant. They can also be set to operate atomically
for any height of lift.
These types are all subject to much concussion and vibration, because the machines are self-contained; anvil, standards and heads being rigidly bolted together, the concussion of every blow is transmitted through the entire mechanism. The Brett hammers (fig. 60) are designed to lessen this, in some cases by making the anvil distinct from the superstructure, and in all by connecting the lifting ropes to the ends of long levers which act something like elastic springs, absorbing vibration. The driving mechanism is also original, comprising a cylinder with a wing piston, which is rotated by steam pressure through an arc of a circle only, sufficiently to operate the lifting levers. Another advantage is that the lifter cylinder need ere.
not be immediately over the hammer, but may be situated elsew The hammer can be operated by hand directly for each stroke. or be set to work automatically.
effect the consolidation of a massive forging right to the centre as a press will. The force of the hammer blow is not transmitted to the centre as is that of a press, nor is the hammer so useful in work of large 'Fl dimensions but of no great weight. 'i In 'railway and wagon shops the' f| presses are used far more frequently it than the hammers. A great advantage of the press is that two and
three rams can be brought into
operation so that a forging may be pressed from above, from below and to one side, which is of great value in complicated forms and in welding, but is not practicable in the hammers. Hence the forging presses have become developed for work of average,
dimensions as well as for the most 1 massive. Many are of horizontal type,
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lxff -~-i i i, Power presses or wor ing sheet;?§ ; a;.f;'?§ Lei.;§ ';L:di.§ ';§ s§ mag' — A it r .-3 "' " - - . a f 1 ' - 'IB 1':::2f'I'-'3E5.¢<'§ .f ~ U1“W|ii'|E!|!|g E yllilfll out or blanking presses, and those ':§ 5= =;"f~§ '.'§ 1';¥;T§ Ei:§ =' »§ :}§ f'i
- I for cupping or drawing the flat blank E g;-§ ~;F: § jS'?:
~/.= .=. ” ' == .=..=, ii* “' ' ' , ' into sha e if desired (fig. 62). The ~'° 'i' ", . . . . P, . ““ if Ei: ~ ~ *FT lower dies are held upon a bed, and "" ~ ' ' ' " I 1 “ "§ ' the up er in a sliding ram moved FIG 61 -Hydraulic Forg Q E up and) down by a cam of crank- ing Press.. (Fielding&Platt, I 1 ¢ lift shaft. A clutch mechanism is fitted, Ltd., Gloucester.) Q ' § I, 'f by means of which this shaft is A Table
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re emfy “Vmg'W ee at “fl fo C, Drawback ram for return- , », Z . rma-Q
D ' V T ~i='! § €¥§ k& i§ , “iiieSf§§ '.i'° if fhiefifs °i i“g B I state the ram remains stationary at' Q' g§ , § Z.g§§ ;;13:f;.eS | }f, ;§ | the top position. The lightest presses | ' Y, f lil); I are driven direct by belt on the crank-shaft pulley, but in the heavier - Q will classes spur-gearing must be interposed between the pulley shaft ! » 1 1, nfifr and the final shaft. The operation of drawing requires an encircling pl | G inf die which presses on the blank as it lies on its die, the cu in
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FIG. 60.-5 cwt. Belt Drop Hammer with Brett's Lifter. i ® (Brett's Patent Lifter Co., Ltd., Coventry.) A, A, Uprights. 11, Buffer bl<}c€<s which arrest B, Anvi . motion o ever c., , 5-C, T . d, L f ' l - ' ""'““$
D B;11i; SS; 0;):, £;l§)mauc regu a Sectional Elevation. Front Elevation. E, Lifter cylinder. ], Lever for regulating amount FIG. 62.-Power Press. C551
of opening of valve by hand.
Valve casing.
Rod operating valve by K, Foot lever for holding tup in either of the stops L.
Spring for foot lever.
lever H.
a, Rock shaft. e,
Spring Hammers are a rather smaller group than the others. In these a belt-driven pulley actuates the tup through the medium of elastic leaf springs. The length of stroke is ad]ustable across the face of a slotted disk on the driving shaft. Forging Machines.-The Ryder forging machine is fitted with four or five pairs of swage tools, the lower halves being fixed and the upper ones driven by a rotating eccentric shaft. The operations imitate those on the anvil by hand forging, but from 800 to 1200 blows are delivered in a minute. The swages are arranged in succession, so that an operation is begun at one end and finished at the other, the attendant moving the bar rapidly through the successive swages or dies.
Forging Presses.-These are rivals to the hammers, especially for heavy forgings, from which hammers are being rapidly displaced (fig. 61). It is now well understood that a hammer will not A, Main frame.
B, Bed for attaching dies.
C, Central slide.
D, Outer slide.,
E, Belt pulleys on shaft, geared to wheel F thrown in by clutch to drive its shaft, which has two crank pins to reciprocate D and a cam disk actuating C.
G Extractor rocked downwards as slide rises to raise lever H and work an ejector rod, forcing finished article out of die. This is why the machine shown in fig. 62 has an outer slide D, which is made to “ dwell ” with an even pressure, while the middle ram is movin down and drawing out the article. Blanking and cupping may be § one as one continuous operation if the work is shallow. I nclinable presses are employed for certain classes of work, the object being to let the stamped articles slide down the slope of the bed as rapidly as they are produced, instead of having to be removed by the operator. Much work can be placed on the dies by hand, but for producing large quantities of small articles automatic feeds
