Fig. 2865Fig. 2865.
Fig. 2865.
Fig. 2866Fig. 2866.
Fig. 2866.
Fig. 2867Fig. 2867.
Fig. 2867.
Swages for trip hammers or for small steam hammers are for work not exceeding about 4 inches in diameter, made as inFig. 2865, the weight of the top swage being sufficient to keep the two closed as in the figure; for larger sizes the bottom swage fits to the anvil, and the top one is provided with a handle, as inFig. 2866,brepresenting the anvil block,s′the bottom, andsthe top swage, having a handleh. The flange of the bottom swage is placed as inFig. 2867, so as to prevent the swage from moving off the anvil block when the work is pushed through it endways. Obviously such swages are employed when the part to be swaged is less in length than the width of the hammer or of the anvil face.
If the hammer and anvil face is rounded as inFig. 2868, or if dies thus shaped are placed in them, their action will be the same as that of the fuller, drawing the work out lengthways, with a minimum of effect in spreading it out sideways.
Detached fullers, such as shown inFigs. 2869and2870, are, however, used when the section to be acted upon is less in length than the hammer face.
In the case of trip hammers, steam hammers, &c., blocks fitted to the hammer and anvil block may take the place of detached swages and fullers. Thus, inFig. 2871is represented the hammer and anvil block for flat work, the corners being made rounded, because if left sharp they would leave marks on the work. The blocks or diesaandbare dovetailed into their places, and secured by keysk; hence they may be removed, and dies of other shapes substituted.
When the work is parallel it may be forged to its finished dimensions by forming in the lower die recesses whose depth equals the required dimensions. Thus, inFig. 2872the recessain the lower die equals in depth the depthaof the work, while the depth of the recessbin the die equals the thickness of the bar; hence by passing the work successively fromatob, and turning it over a quarter turn, it will be made to finished size, when the facesc dof the dies meet.
For this class of work the recesses must obviously be made in the lower die, because it would be difficult to hold the work upon the lower die in the proper position to meet a recess cut in the upper one: and, furthermore, the recesses in the die should be wider than the work, to avoid the necessity of holding the work exactly straight in the recess, and keeping it against the shoulder or vertical face of the recess. If, however, the work is to be made taper, we may obviously make the recess taper, so as to produce smooth work, the die recess being made to be of the correct depth for the smallest end of the work.
When the shape of the work is such that it cannot be moved upon the die during the forging, the operation is termed stamping, or if the hammer or upper die falls of its own weight it is termed drop forging, and in this case the finishing dies are made the exact shape of the work, care being taken to let the work beenveloped as much as possible by the bottom die, so that the top one shall not lift it out on its up stroke.
In forging large pieces from square to round we have several important considerations. In order to keep the middle of the work sound, it must be drawn square to as near as possible the required diameter before the finishing is begun. During this drawing-down process the blows are heavy and the tendency of the work is to spread out at the sides, as inFig. 2873.
When the work is ready to be rounded up it is first drawn to an octagon, as shown inFig. 2874, so as to bring it nearer the work, nearer to cylindrical form. The corners are then again hammered down, giving the work sixteen sides, the work during this part of the process being moved endways, as each corner is hammered down. The blows are during this part of the forging lighter, but still the tendency is to spread the work out sideways. The final finishing to cylindrical form is done with light blows, the work being revolved upon the anvil without being moved endways, so that a length equal to the width of the anvil is finished before the work is moved endways to finish a further part of the length. The tendency to spread sideways is here unchecked, because the iron is squeezed top and bottom only. We may check it to some extent, however, by employing a bottom swage block, as inFig. 2875, in which case the contact of the swage and the work will extend further around the work circumference than would be the case with a flat anvil. If we were to use a top and a bottom swage, as inFig. 2876, the circumferential surface receiving the force of the blow will be still further increased, but there will still be a tendency to spread at the sides, as ata b, inFig. 2876. A better plan, therefore, is to use aV-block with the hammer, as inFig. 2877, in which case the effects of the blow are felt ata,b, andc, and the pointsa bof resistance being brought higher up on the work, its tendency to spread is obviously diminished. By using a top and bottomV-block, as shown inFig. 2878, the effect will be to drive the metal towards the centre, and, therefore, to keep it sound at the centre, it being found that if the metal is swaged much without means being taken to prevent spreading, it “hammers hollow,” as it is termed, or in other words, splits at its centre.
Fig. 2879Fig. 2879.
Fig. 2879.
The pointsa bof resistance to the blow atcare higher and the tendency to spread sideways is better resisted. For cutting off under the steam hammer, the hack shown inFig. 2879is used, being simply a wedge with an iron handle.
Welding.—In the welding operations of the blacksmith there are points demanding special attention: first, to raise the temperature of the metal to a proper heat; second, to let the temperature be as nearly equal as practicable all through the mass; third, to have the surfaces to be welded as clean and free from oxidation as possible; fourth, have the parts to be welded of sufficient diameter or dimensions to permit of the welded joint being well forged.
The following remarks on the theory of welding are from a paper read by Alexander L. Holley before the American Institute of MiningEngineers:—
“The generally received theory of welding is that it is merely pressing the molecules of metal into contact, or rather into such proximity as they have in the other parts of the bar. Up to this point there can hardly be any difference of opinion, but here uncertainty begins. What impairs or prevents welding? Is it merely the interposition of foreign substances between the molecules of iron, or of iron and any other substance which will enter into molecular relations or vibrations with iron? Is it merely the mechanical preventing of contact between molecules, by the interposition of substances? This theory is based on such facts as the following:
“1. Not only iron but steel has been so perfectly united that the seam could not be discovered, and that the strength was as great as it was at any point, by accurately planing and thoroughly smoothing and cleaning the surfaces, binding the two pieces together, subjecting them to a welding heat, and pressing them together by a very few hammer blows. But when a thin film of oxide of iron was placed between similar smooth surfaces, a weld could not be effected.
“2. Heterogeneous steel scrap, having a much larger variation in composition than these irons have, when placed in a box composed of wrought-iron side and end pieces laid together, is (on a commercial scale) heated to the high temperature which the wrought-iron will stand, and then rolled into bars which are more homogeneous than ordinary wrought iron. The wrought-iron box so settles together as the heat increases that it nearly excludes the oxidizing atmosphere of the furnace, and no film of oxide of iron is interposed between the surfaces. At the same time the enclosed and more fusible steel is partially melted, so that the impurities are partly forced out and partly diffused throughout the mass by the rolling.
“The other theory is that the molecular motions of the iron are changed by the presence of certain impurities, such as copper and carbon, in such a manner that welding cannot occur, or is greatly impaired. In favor of this theory it may be claimed that, say, 2 per cent. of copper will almost prevent a weld, while, if the interposition theory were true, this copper could only weaken the weld 2 per cent., as it could only cover 2 per cent. of the surfaces of the molecules to be united. It is also stated that 1 per cent. of carbon greatly impairs welding power, while the mere interposition of carbon should only reduce it 1 per cent. On the other hand, it may be claimed that in the perfect welding due to the fusion of cast iron, the interposition of 10 or even 20 per cent. of impurities, such as carbon, silicon, and copper, does not affect the strength of the mass as much as 1 or 2 per cent. of carbon or copper affects the strength of a weld made at a plastic instead of a fluid heat. It is also true that high tool steel, containing 11⁄2per cent. of carbon is much stronger throughout its mass, all of which has been welded by fusion, than it would be if it had less carbon. Hence copper and carbon cannot impair the welding power of iron in any greater degree than by their interposition, provided the welding has the benefit of that perfect mobility which is due to the fusion. The similar effect of partial fusion of steel in a wrought-iron box has already been mentioned. The inference is, that imperfect welding is not the result of a change in molecular motions due to impurities, but of imperfect mobility of the mass—of not giving the molecules a chance to get together.
“Should it be suggested that the temperature of fusion, as compared with that of plasticity, may so change chemical affinities as to account for the different degrees of welding power, it may be answered that the temperature of fusion in one kind of iron is lower than that of plasticity in another, and that as the welding and melting points of iron are largely due to the carbon they contain, such an impurity as copper, for instance, ought, on this theory, to impair welding in some cases and not to affect it in others.
“The obvious conclusions are: 1st. That any wrought iron, of whatever ordinary composition, may be welded to itself in an oxidizing atmosphere at a certain temperature, which may differ very largely from that one which is vaguely known as ‘a welding heat.’ 2nd. That in a non-oxidizing atmosphere heterogeneous irons, however impure, may be soundly welded at indefinitely high temperatures.
“The next inference would be that by increasing temperature we chiefly improve the quality of welding. If temperature is increased to fusion, welding is practically perfect; if to plasticity and mobility of surfaces, welding should be nearly perfect. Then how does it sometimes occur that the more irons are heated the worse they weld?
“1. Not by reason of mere temperature, for a heat almost to dissociation will fuse wrought iron into a homogeneous mass.
“2. Probably by reason of oxidation, which, in a smith’s fire especially, necessarily increases as the temperature increases. Even in a gas furnace a very hot flame is usually an oxidizing flame. The oxide of iron forms a dividing film between the surfaces to be joined, while the slight interposition of the same oxide, when diffused throughout the mass by fusion or partial fusion, hardly affects welding. It is true that the contained slag, or the artificial flux, becomes more fluid as the temperature rises, and thus tends to wash away the oxide from the surfaces; but inasmuch as any iron with any welding flux can be oxidized till it scintillates, the value of a high heat in liquefying the slag is more than balanced by its damage in burning the iron.
“But it still remains to be explained why some irons weld at a higher temperature than others; notably, white irons high in carbon, or in some other impurities, can only be welded soundly by ordinary processes at low heats. It can only be said that these impurities, as far as we are aware, increase the fusibility of iron, and that in an oxidizing flame oxidation becomes more excessive as the point of fusion approaches. Welding demands a certain condition of plasticity of surface; if this condition is not reached, welding fails for want of contact due to mobility; if it is exceeded, welding fails for want of contact due to excessive oxidation. The temperature of this certain condition of plasticity varies with all the different compositions of irons. Hence, while it may be true that heterogeneous irons, which have different welding points, cannot be soundly welded to one another in an oxidizing flame, it is not yet proved, nor is it probable, that homogeneous irons cannot be welded together, whatever their composition, even in an oxidizing flame. A collateral proof of this is, that one smith can weld irons and steels which another smith cannot weld at all, by means of a skilful selection of fluxes and a nice variation of temperatures.
“To recapitulate. It is certain that perfect welds are made by means of perfect contact due to fusion, and that nearly perfect welds are made by means of such contact as may be got by partial fusion in a non-oxidizing atmosphere or by the mechanical fitting of surfaces, whatever the composition of the iron may be within all known limits. While high temperature is thus the first cause of that mobility which promotes welding, it is also the cause, in an oxidizing atmosphere, of that ‘burning’ which injures both the weld and the iron. Hence, welding in an oxidizing atmosphere must be done at a heat which gives a compromise between imperfect contact due to want of mobility on the one hand, and imperfect contact due to oxidation on the other hand. This heat varies with each different composition of irons. It varies because these compositions change the fusing points of irons, and hence their points of excessive oxidation. Hence, while ingredients such as carbon, phosphorus, copper, &c., positively do not prevent welding under fusion, or in a non-oxidizing atmosphere, it is probable that they impair it in an oxidizing atmosphere, not directly, but only by changing the susceptibility of the iron to oxidation.”
In welding steel to iron both are heated to as high a temperature as possible without burning, and a welding compound or flux of some kind is used.
In welding steel to steel the greatest care is necessary to obtain as great a heat as possible without burning, and to keep the surfaces clean.
An excellent welding compound is composed as follows: Copperas 2 ozs., salt 4 ozs., white sand 4 lbs., the whole to be mixed and thrown upon the heat, as is done when using white sand as described for welding iron. An equally good compound is made up of equal quantities of borax and pulverized glass, well wetted with alcohol, and heated to a red heat in a crucible. Pulverize when cool, and apply as in the case of sand only.
A welding compound for cast steel given by Mr. Rust in theRevue Industrielleis made up as follows: 61 parts of borax, 20 parts of sal-ammoniac, 163⁄4parts of ferrocyanide, and 5 parts of colophonium. He states that with the acid of this compound cast steel may be welded at a yellow red heat, or at a temperature between the yellow, red, and white heats. The borax and sal-ammoniac are powdered, mixed, and slowly heated until they melt. The heating is continued until the strong odor of ammonia ceases almost entirely, a small quantity of water being added to make up for that lost by evaporation. The powdered ferrocyanide is then added, together with the colophonium, and the heating is continued until a slight smell of cyanogen is noticed. The mixture is allowed to cool by spreading it out in a thin layer.
Fig. 2880Fig. 2880.
Fig. 2880.
Fig. 2881Fig. 2881.
Fig. 2881.
The lap weld is formed as follows: Suppose it is required to weld together the ends of two cylindrical pieces, and the first operation is to pump or upset the ends to enlarge them, as shown inFig. 2880, so as to allow some metal to be hammered down in making the weld without reducing the bar below its proper diameter. The next operation is to scarf the ends forming them, as shown inFig. 2881, and in doing this it is necessary to make the scarf face somewhat rounding, so that when put together as in the figure contact will occur at the middle, and the weld will begin there and proceed as the joint comes together under the blows towards the outside edges. This squeezes out scale or dirt, and excludes the air, it being obvious that if the scarf touched at the edges first, air would be enclosed that would have to find its escape before the interior surfaces could come together.
It is obvious, that if the two pieces require to weld up to an exact length and be left parallel in diameter when finished an allowance for waste of iron must be made; and a good method of welding under these conditions is asfollows:—
Fig. 2882Fig. 2882.
Fig. 2882.
Fig. 2883Fig. 2883.
Fig. 2883.
Let the length of the two pieces be longer than the finished length to an amount equal to the diameter. Then cut out a piece as ata, inFig. 2882, the step measuring half the diameter of the bar as shown. The shoulderais then thrown back with the hammer, and the piece denoted by the dotted linebis cut off, leaving the shaft as shown inFig. 2883.
The faces of the scarf should be somewhat rounding, so that when the weld is put together contact will take place in the centre of the lapping areas. Then, as the surfaces come together, the air and any foreign substances will be forced out, whereas, were the surfaces hollow the air and any cinder or other foreign substances would be closed in the weld, impairing its soundness.
Fig. 2884Fig. 2884.
Fig. 2884.
The lap of the two pieces, when scarfed in this manner, is shown inFig. 2884.
To take the welding heat the fire should be cleaned out and clear coked coal, and not gaseous coal, used. The main points in a welding heat are, to heat the iron equally all through, to obtain the proper degree of heat, and to keep the scarfed surfaces as free from oxidation, and at the same time as clean, as possible.
To accomplish these ends the iron must not be heated too quickly after it is at a good red heat, and the fire must be so made that the blast cannot meet it at any point until it has passed through the bed of the fire.
When the iron is getting near the welding heat it may be sprinkled with white sand, which will melt over it and form a flux that will prevent oxidation and cool the exterior, giving time to the interior to become equally heated. The sand should be thrown on the work while in the fire, as removing the work from the fire causes it to oxidize or scale rapidly. The work should be turned over and over in the fire, the scarf face being kept uppermost until the very last part of the heating, when the blast must be put on full, the bed of the fire kept full and clear so that there shall be sufficient bed to prevent the blast from meeting the heat until it has passed through the glowing coals.
When the heat is taken from the fire it should meet the anvil with a blow, the scarfed face being downwards, to jar off any dirt, cinder, &c., and the scarf should be cleaned by a stroke or two of a wire brush. But as every instant the iron is in the air it is both cooling and oxidizing, these operations must be performed as quickly as possible.
The two scarfs being laid together as shown inFig. 2884, the first blows must be delivered lightly, so as not to cause the upper piece to move, and as quickly as possible, the force of the blows being increased regularly and gradually until the weld is sufficiently firm to hold well together, when it may be turned on edge and the edges of the scarf hammered to close and weld the seam. If this turning is done too soon, however, it may cause the two halves to separate. When the weld is firmly and completely made the enlarged diameter due to the scarfing may be forged down, working the iron as thoroughly as possible.
Fig. 2885Fig. 2885.
Fig. 2885.
Fig. 2886Fig. 2886.
Fig. 2886.
To form the scarf of a ring or collar, one end is bevelled, as atbinFig. 2885and after the piece is bent to a circle it is cut off and bevelled as ata. When a slight band is to be welded, and it is difficult to steady the ends to bring them together, a clamp may be used to hold them as inFig. 2886.
Fig. 2887Fig. 2887.
Fig. 2887.
Fig. 2887represents a tongue weld, and it is obvious that to insure soundness the wedge piece should fit in the bottom of the split, which may be well closed upon it by the hammer blows.
Fig. 2888Fig. 2888.
Fig. 2888.
Fig. 2888represents an example of aV-weld applied to welding up a band that is to be square when finished, and as the lengths of the sides must be equal when finished, the side on which the weld is made should be made shorter, so that in stretching under the welding blows it will be brought to its proper length. TheVform of weld is employed because it stretches less in welding than the lap weld. TheV-piece to be welded in should bear at the bottom of theV, and the weld made by fullering.
Fig. 2889Fig. 2889.
Fig. 2889.
Fig. 2890Fig. 2890.
Fig. 2890.
Fig. 2891Fig. 2891.
Fig. 2891.
Fig. 2892Fig. 2892.
Fig. 2892.
Fig. 2893Fig. 2893.
Fig. 2893.
Welds of this kind are obviously most suitable for cases in which the weld is required to influence the shape of the piece as little as possible. The figures above, which are taken fromMechanics, illustrate as an example the repairing of a broken strap for the beam of a river steamboat. The crack is ata,Fig. 2889, and is held together by a clamp as shown; aV-recess is cut out as inFig. 2890, and this recess is fullered larger, as inFig. 2891. AV-block is then welded in. The strap is thenturned over a secondV-groove, cut out and fullered out, and a secondV-piece welded in. By thus welding one side at a time the welding is taken in detail as it were, and the blows can be less heavy than if a larger weld were made at one heat, as would be the case if but oneVblock were used. A similar form of weld may be employed to form a square corner, as is shown inFig. 2892, which is taken from “The Blacksmith and Wheelwright.” In this example the inside corner is shown to have a fillet, which greatly increases the difficulty of the job. The weld is made by first fullering theV-piece on the sides and on the rounded corner and then laying the piece on the anvil to forge down, the fullering leaving the finished job as inFig. 2893.
Fig. 2894Fig. 2894.
Fig. 2894.
Fig. 2895Fig. 2895.
Fig. 2895.
When one piece has to be driven on to the other, the weld is called a pump-weld, for which the ends should be rounded as inFig. 2894, so that they will meet at their centres, and will, when struck endways to make the weld, come to the shape shown inFig. 2895.
Fig. 2896Fig. 2896.
Fig. 2896.
It is obvious that in this case the interior of the iron comes together and is welded, and that dirt, &c., is effectually excluded; hence if the iron is properly heated the weld may be as sound as a lap weld, and is preferred by many as the sounder weld of the two. When a stem requires to be welded to a large flat surface, the pump weld is the only one possible, being formed as inFig. 2896, in which the stem is supposed to be welded to a frame. The plate is cupped as shown, and the metal being driven up on the sides as much as possible, the stem overlaps well atc b, so that it may be fullered there. The stem should first meet its seat ata, so that dirt, &c., may squeeze out as the welding proceeds.
Fig. 2897Fig. 2897.
Fig. 2897.
Fig. 2898Fig. 2898.
Fig. 2898.
Figs. 2897and2898represent an example of welding a collar on round iron. The bar is upset so as to enlarge it ata, where the collar is to be. The collar is left open at the joint, and while it is cold it is placed on the red-hot bar and swaged until the ends are closed. The welding of the whole may then be done at one heat, swaging the outside of the collar first. Unless the bar is upset there would be a crack in the neckbof the collar on both sides.
Welding Angle Iron.—Let it be required to form a piece of straight angle iron to a right angle.
Fig. 2899Fig. 2899.
Fig. 2899.
The first operation is to cut out the frog, leaving the piece as shown inFig. 2899; the width at the mouthaof the frog being3⁄4inch to every inch of breadth measured inside the flange as atb.
The edges of the frog are then scarfed and the piece bent to an acute angle; but in this operation it is necessary to keep the scarfs quite clean and not to bend them into position to weld until they are ready for the welding heat; otherwise scale will form where the scarfs overlap and the weld will not be sound.
The heat should be confined as closely as possible to the parts to be welded; otherwise the iron will scale and become reduced below its proper thickness.
Fig. 2900Fig. 2900.
Fig. 2900.
The iron is then bent to the shape shown inFig. 2900; and the angle to which it is bent is an important consideration. The object is to leave the overlapping scarf thicker than the rest ofthe metal, and then the stretching which accompanies the welding will bring the two arms or wings to a right angle.
Fig. 2901Fig. 2901.
Fig. 2901.
It is obvious, then, that the thickness of the metal at the weld determines the angle to which the arms must be bent before welding. The thicker the iron the more acute the angle. If the angle be made too acute for the thickness of the iron at the weld there is no alternative but to swage the flange down and thin it enough to bring the arms to a right angle. Hence it is advisable to leave the scarf too thick rather than too thin, because while it is easy to cut away the extra metal, if necessary, it is not so easy to weld a piece in to give more metal. In very thin angle irons, in which the wastage in the heating is greater in proportion to the whole body of metal, the width of the frog atainFig. 2901may be less, as, say,9⁄16inch for every inch of angle-iron width measured as atbin the figure. For angles other than a right angle the process is the same, allowance being made in the scarf-joint and bend before welding for the stretching that will accompany the welding operation.
The welding blows should be light and quick, while during the scarfing the scale should be cleaned off as soon as the heat leaves the fire, so that it will not drive into the metal and prevent proper welding. The outside corner should not receive any blows at its apex; and as it will stretch on the outside and compress on the inside, the forging to bring the corner up square should be done after the welding.
The welding is done on the corner of an angle block, as inFig. 2901, in whichais the angle iron andbthe angle block.
Fig. 2902Fig. 2902.
Fig. 2902.
To bend an angle iron into a circle, with the flange at the extreme diameter, the block and pins shown inFig. 2902are employed. The block is provided with the numerous holes shown for the reception of the pins. The pins marked 1 and 2 are first inserted and the iron bent by placing it between them and placed under strain in the necessary direction. Pins 3 and 4 are then added and the iron again bent, and so on; but when the holes do not fall in the right position, the length of the pin-heads vary in length to suit various curves.
To straighten the iron it is flattened on the surfaceaand swaged on the edge of the flangeb, the bending and straightening being performed alternately.
Fig. 2903Fig. 2903.
Fig. 2903.
When the flange of the angle iron is to be inside the circle, as inFig. 2903, a special iron made thicker on the flangeais employed. The bending is accomplished, partly by the pins as before, and partly by forging thinner, and thus stretching the flangeawhile reducing it to its proper thickness.
To Forge a Bolt by Hand.—The blanks for bolts must be cut off sufficiently long to admit of one end being upset to form the head, the amount of this allowance, obviously, being determined by the size of the head.
Fig. 2904Fig. 2904.
Fig. 2904.
Fig. 2905Fig. 2905.
Fig. 2905.
Fig. 2904is a side view, partly in section, andFig. 2905a top view of an anvil block for upsetting the ends of blanks to form the heads of bolts. The stem fits into the square hole of the anvil. The tongue is pivoted as shown in the top view to two lugs provided on the block; upon the tongue rests a steel pin whose length determines the height to which the blank will project above the top of the block, and, therefore, the amount or length of blank that will be upset to form the head, this amount being three times the diameter of the bolt forblack heads.
Fig. 2906Fig. 2906.
Fig. 2906.
The hole for the blank is made about1⁄64inch larger in diameter than the designated size of the bolt, to permit of the easy extraction of the blank after it is upset, this extraction being accomplished by striking the end of the tongue with the hammer. If the block is made of cast iron the upper end of the hole will become worn after forging five hundred or six hundred bolts, leaving the bolts with a rounded neck, as atc cinFig. 2906; a steel block, however, will forge several thousand bolts without becoming enlarged.
Fig. 2907Fig. 2907.
Fig. 2907.
An excellent plan is to provide the block with removable dies, such as atd dinFig. 2907, which are easily renewed, a number of such dies having different diameters of bore fitted to the same block.
When the bolt end is sufficiently reset or enlarged to form the head it is laid in a bottom swage, containing three of the six sides of the hexagon, and a hammer blow on the uppermost part of the end forges a flat side. After each blow the work is revolved one-sixth of a revolution, and as the angles of the swage are true they obviously true the angles of the bolt head. After the head has been roughed down it is necessary to flatten it again under the head and on the end, for which purpose it may be placed in the heading block shown inFig. 2904, after which the sides of the head may be finished and the cupping tool for chamfering the head applied.
The bolt may require passing from the heading tool to the swage several times, as forging it in one direction spreads it in another.
Fig. 2908Fig. 2908.
Fig. 2908.
In shops where bolt-making is of frequent occurrence a special bolt-making device is usually employed. It consists of an oliver or foot hammer, having two hammers and an anvil; in the square hole at one end of the anvil fits a hardy or bottom chisel, such as shown inFig. 2908, for cutting up the bar or rod iron into bolt blanks;ais the anvil,hthe hardy, andga gauge to determine the length cut off the rodrto form a blank. An upsetting or heading device corresponding to that inFig. 2907is provided, and at the other end of the anvil is the swage for forming the bolt head.
The object of having two hammers is that one may be used for the upsetting of the blank and the other for the swage. The swaging hammer is provided with a hole and set-screw to receive top swages, and bolt hammers are adjustable for height so that they may be set so that their faces will meet the work fair.
Fig. 2909Fig. 2909.
Fig. 2909.
Fig. 2910Fig. 2910.
Fig. 2910.
Fig. 2911Fig. 2911.
Fig. 2911.
Figs. 2909to2911represent front, side, and top views of Pratt & Whitney’s portable bolt-forging device. It is provided with an elevating screw that permits the employment of a single bolster-pin for all lengths of bolt for a given diameter, instead of requiring a separate pin for each different length of bolt. In the figures,ais a frame carried upon wheels, and to which is pivoted atc cthe jawd. The bolt-gripping dies are shown ate f. A treadlegis pivoted ath, and acts upon the lower end ofd, causing the diefto grip or release the bolts, as may be required. The bolster-pin rests upon the end of the screwi, which enters at its foot a split nutj, which is caused to grip and lock the screw by operating the nut of the boltkthat passes through the split of the nut.lis a spring that lifts the treadle when it is relieved of the pressure of the operator’s foot.
Atmis a leather washer to protect the nutjfrom the scale that falls from the forging. The operation is asfollows:—
The nutkis released and the screwioperated to suit the length of bolt required. Thenjis caused to clamp the screw by operating the nutk. The blank for the bolt is placed in the dies resting on the bolster-pin, which in turn rests upon the end of the screwi. The treadlegis depressed, and the bolt blank clamped betweeneandf. The helper then with the sledge upsets the blank end to form the bolt head, and the blacksmith forges it to shape in the former barb, which is provided with impressions for the form of head required, these impressions being of varying sizes, as shown. The device is so strongly proportioned as to be very solid, and is found to be a most useful addition to the blacksmith’s shop.