William L. Ilgen

112. A Forging.—A forging is an article made of metal, generally steel or iron, and produced by heating and hammering. It may be used for either practical or ornamental purposes. The various forgings already described were made by methods such as the older class of smiths practiced, and are called hand forgings. From a practical standpoint these smiths were familiar with the characteristic composition of metals and with the knowledge of how they should be worked.

Many forgings are produced at present by machinery. The product is satisfactory for most practical purposes, and is generally equal to that made by hand. The machines used are the drop hammers, horizontal and vertical presses, steam hammers, and numerous other devices. The power used for operating them may be either steam, air, water, or electricity.

113. The Drop Hammer.—The drop hammer is provided with a pair of dies made of cast steel, one upper and one lower, having suitably shaped depressions made in them for forming the forgings. The lower die is held stationary on a solid foundation block, and the upper one is secured to a heavy weight or hammer. This is raised perpendicularly and allowed to drop upon the metal, which is held on the fixed die by the smith, thus forming the forging.

If the work is small and simple, all depressions may be made in a single pair of dies, and the forging can be completed with one hammer and without changing the dies. Work somewhat complicated may require two or more pairs of dies, with various shapes of depressions. The stock is broken down or blocked out by the first pair and then completed by the stamping and finishing dies. Larger pieces may require also a number of pairs of dies, then an equal number of hammers may be used, each fitted with a set of dies. The material is passed from one to the other, and the work completed without changing dies, and possibly without reheating the metal.

114. Presses.—Presses may be either horizontal or vertical and are generally used for bending or pressing the metal into some desired shape or form; they are quite convenient for producing duplicate and accurate shapes. Forming-dies or blocks are also required here, but they are generally made of cast iron, and their construction need not be so accurate. After the presses have been properly adjusted, very little skill is required in their operation,—simply the heating of the material and placing it against a gauge or between the dies. One thrust of the plunger will complete the operation.

115. The Steam Hammer.—The steam hammer was first recorded by Mr. James Nasmyth in his “scheme book” on the 24th of November, 1839. Although this was the exact date of its origin, he first saw it put into practical use by the Creuzot Iron Works of France in 1842. Nasmyth’s invention legally dates from June, 1842, when his patent was procured.

Of the various machines that have been devised for the smith’s use, to relieve him of the laboriousness of pounding metal into shape, there is none that could take the place of this invention. Numerous shapes and forms can be produced more accurately and rapidly by the employment of the steam hammer than by the use of hand methods.

Fig. 101.—A Steam Hammer Equipped with a Foot Lever.

Before proceeding any further, a few words of warning and advice may not be out of place. Although this invention is a great benefactor to the smith, it is not possessed with human intelligence, nor is it a respecter of persons. The power of steam will always exert its utmost force when liberated, so do not let in too much steam at first. Unless the material is held horizontally and flat on the die, the blow will jar the hands badly and will bend the material. All tools such as cutters and fullers should be held firmly but lightly, so that they may adjust themselves to the die and the descending blow.

After the hammer has been put into motion, the blows will fall in a perfectly routine manner. By his careful observation and a thorough understanding of the necessary requirements, and by signals from the smith, the hammer operator should regulate the force of the blows to suit the smith’s convenience.

A caution pertaining to the tongs used for handling the material should be carefully observed. Whenever work is to be forged with the steam hammer, the material should be held with perfect-fitting tongs secured by slipping a link over the handles; a few light blows delivered on the link will tighten their grip.

116. Steam Hammer Tools.—First some necessary tools will be explained, then exercises requiring their use will be given, followed by a few operations where simple appliances are needed.

117. The hack or cutter (Fig. 102) is used for nearly the same purposes as the hot cutter already described. It should be made of tool steel from 0.80 to 0.90 per cent carbon. The head or top is made convex, as shown, and not more than ⁵/₈ inch thick, tapering equally on both sides to the cutting edge, which may be made either ³/₁₆ or ¹/₄ inch thick. It should be ground straight and parallel to the top and tempered to a dark blue.

The blade is about 2¹/₄ or 2¹/₂ inches wide, unless intended for heavy forgings, when all dimensions should be increased. The width of the blade should not be too great, however, for the broader the cutter, the greater its liability to glance sidewise or turn over when the blows are delivered upon it. The length of this cutter may be from 3³/₄ to 4 inches.

The handle may be about 28 inches long, approximately ³/₄ inch in diameter at a and gradually tapered towards the end, where it is about ¹/₂ inch. The portion indicated at b is flattened to an oblong section, as shown, to allow springing when the blows are delivered and to prevent bruising the hands.

118. The circular cutter (Fig. 103) is made of the same material and with a handle of similar dimensions and form as the hack. A section of the cutting portion on a-a is shown, and suitable dimensions given. If convex ends are to be cut, the perpendicular side of the blade should always be on the inner side of the curve, but on the outer side for concave ends.

An assortment of these cutters with various-sized arcs may be provided to suit requirements, but quite frequently the curved cutting portion is altered to suit the particular work at hand.

119. The trimming chisel (Fig. 104) is made quite similar to an ordinary hot cutter and likewise provided with a wooden handle. It should be strongly constructed, perfectly straight on one side, and not too long from the cutting edge to the top to avoid its being turned over when the blows are delivered upon it. The grinding should be done on the tapered side only, with the cutting edge tempered to a dark blue.

120. The cold cutter (Fig. 105) is used for purposes similar to those of the ordinary cold cutter. It should be strongly made in a triangular form, as shown in the end view, also with a spring handle like that of the hack. The top is made convex, and the sides taper to the cutting edge, which should be ground equally from both sides. It should be carefully tempered for cutting cold material.

In cutting stock with this tool, the material should be nicked sufficiently deep on the exterior to allow it to be broken. By holding the piece securely with the hammer, and the nicked portion even with the edge of the dies, it may be broken off by a few blows from a sledge. The steam hammer may also be used to break the stock when nicked with the cold cutter. The piece should be placed on the lower die of the hammer, as shown in Fig. 106, and broken by one or two sharp blows from the hammer. A piece of round stock can be used instead of the triangular piece of steel, with the same result. When material is being broken in this way, see that no one is standing in a direct line with the stock, as there is some liability of one or both pieces flying in either direction.

When using the hack (Fig. 102) for cutting square stock, cut equally from all sides, as shown at a, Fig. 107. This will produce smoother ends than if it were cut unequally and will prevent the short end from turning upward when the final blows are delivered. The fin or core that is formed by the hack, shown at b, generally adheres to one of the pieces, but it can be removed by using the trimming chisel in the manner shown. These fins are commonly removed by the use of an ordinary hot cutter and sledge.

The hack, if held perpendicularly, will not cut the end of either piece square. If one end is to be cut square, the cutter should be held as shown at c. Round material may be cut similarly, but to avoid marring its circular section it may be held in a swage fitted to the hammer die.

Flat stock may be cut equally from both sides, or if it is cut nearly through from one side, the operation can be completed by placing a small piece of square untempered steel over the cut, as shown at e. A sharp blow of the hammer will drive the steel through into the opening and produce a straight, smooth cut.

When a semicircular end is to be produced, similar to that indicated by the broken line at d, the circular cutter should be used. Here, also, the cutting should be done equally from each side.

121. The checking tool or side fuller (Fig. 108) is made of tool steel with a carbon content, the same as for the cutters. The handle also is the same, with the exception of part a, which provides the spring. Here, on account of its being used in two different positions, a twisted form is much better, because the tool may spring in either direction. From the end view you will notice that it has a triangular section with one square corner and two curved ones.

A convenient dimension for this tool is about 2¹/₂ inches over all from the square to the circular corners. It would be convenient to have a smaller one also, of about 1¹/₂ inches. The length of this tool should correspond with that of the cutters.

In use, one of the circular corners of the checking tool is forced into the metal, forming a triangular-shaped depression, as shown at b. Two depressions are shown in this sketch in opposite directions to each other, made by holding the tool in different positions and using both the circular edges. The object of this operation is to set off the rectangular portion b so that the ends c-c can be drawn out without disturbing the center.

122. The fuller (Fig. 109) is made with a handle like that of the checking tool, but the portion used for fullering is made circular in section and about 4 inches long. An assortment of sizes should be provided, with diameters of 1, 1¹/₂, and 2 inches. When smaller sizes are needed, a bar of round steel may be conveniently substituted. These tools may be properly termed top fullers, because they are generally held on top of the metal and the blows are delivered from above, thus forming depressions on one side only. Sometimes double depressions are required directly opposite to each other. In such cases a short piece of round metal, the same size as the fuller, is placed on the die directly under the top fuller, with the metal between the two.

If the depressions are to be only semicircular, a short piece of half-round material may be provided which is not liable to be dislocated or jarred out of position on the die.

123. The combined spring fullers (Fig. 110) are very convenient for making double depressions. They are similar to the single fuller, but are flattened out at a and b, so that they may be opened for various sizes of stock.

124. The combination fuller and set (Fig. 111) may be made with a straight, round handle, but a twisted one is more desirable, because the tool is frequently used in different positions. It should be made of a quality of steel that will withstand severe hammering without becoming battered. The heavy end which forms the tool is made about 1¹/₂ by 2¹/₂ inches; the corners on one side are left sharp and square, while those opposite are made quarter-round. One side of this tool may be made almost semicircular if it is intended to be used as a fuller. The length may be about 4 inches.

This tool is used as a fuller or set in drawing metal between projections which have been formed by using the checking tool. In Fig. 112 the sections of metal, indicated by a and c, are to be drawn to smaller dimensions. This cannot be done with the hammer, because these places are narrower than the width of the hammer dies. At c the fuller or set is being used flatwise, which is the better way, because the two round corners will not cause galling. At a it is shown in use edgewise; but this should not be continued after the opening has been enlarged sufficiently to use the tool as at c, unless perfectly sharp corners are desired.

Another convenient use for this tool is for finishing a roughly drawn tapered piece of metal, as at d. Here are shown the roughened tapered surfaces, as they have been produced by the hammer, also the method of using the set. If there is much of this kind of work to be done, it would be advisable to provide a special tool with a circular side which could be used solely as a flatter.

125. The combined top and bottom swages (Fig. 113) are also called spring swages, because they are somewhat flexible at the connecting loop, which keeps them in adjustment. The best material for these swages, on account of the constant hammering to which they are subjected, is a good quality of mild or soft steel. Much hammering has a tendency to crystallize the metal and causes frequent breakage.

The heavy parts forming the swages ought to be well proportioned and made from sufficiently heavy stock. The handles are drawn out from the same material and welded, or merely stub ends may be drawn from this material, and then flat stock welded on to form the handles. In either case the edges should be swaged half-round previous to welding. The top and bottom of the handles are not parallel with the upper and lower parts of the swages, because the heavy parts only should receive hammer blows.

The grooves should be perfect semicircles, with the exception of the edges indicated at e, which should be slightly round, as shown. This prevents metal from becoming lodged in the swages. If the metal sticks, the smith will be unable to revolve it in the swages, and it will become oblong in section. The corners on top of the upper swage should be removed, as shown, so that the blows will be received more directly through its center.

126. The top and bottom swages (A and B, Fig. 114) are made separate, but of the same quality of material as those just described. The handle of the top swage A, however, should be round, with a small portion flattened, as shown. The bottom swage B is constructed with projecting lugs d, as shown. The distance between the lugs should be equal to the width of the lower hammer die, over which the swage should fit closely enough to prevent its displacement. The swages may be used together or separately, as desired, the lower one being convenient for cutting round material, as it prevents marring the sectional form of the stock.

127. The bevel or taper tool (Fig. 115) is provided with lugs and fits the hammer die. When constructed for general use, the pitch should not be too great, because it may be increased by placing a short piece of metal under one end, as shown, or decreased by inserting metal under the opposite end. The heavy end should be made as nearly perpendicular as possible, with the outer edge of the die. This tool is very handy for drawing any tapering work, such as cold chisels, levers, keys, etc.

128. The V block (Fig. 116) was introduced by the inventor of the steam hammer, and was used instead of a bottom swage. When large, round sections are to be produced, and swages of the proper size are not obtainable, this tool may be used.

When round stock is drawn without a swage, only two portions directly opposite to each other are acted on by the hammer, thus causing some liability of producing an oblong section or a hollow centered forging. These difficulties are avoided to a certain extent by the use of the V block, because the force of the blow acts in three directions.

129. The yoke or saddle (Fig. 117) should be made of heavy flat material bent into the form of a U, with the ends perfectly straight and parallel. It should be provided with lugs fitted to the lower die so that both sides will stand erect and at right angles to it, as at A. The distance between the sides may be of any convenient width, 2¹/₂ inches or more, depending upon the character of the work to be done. Semicircular depressions should be made on the edges, as shown at e.

Another view of the yoke is given at B, with one side removed. As seen here, it is used to draw weldless or solid rings after the stock has been blocked out and a sufficiently large hole has been punched in it to allow it to be hung over the pin p, which rests in the depressions previously mentioned. Hammer blows can be delivered on the exterior of the stock, thus drawing it and increasing its diameter. As this is increased, larger pins should be used, to produce a smoother and more evenly drawn ring.

The yoke, shown at C, is being used as a bridge for drawing the ends of a solid forged jaw. By using it for purposes like this, considerable hand labor may be saved.

130. Bolsters or collars (a, Fig. 118) are used for punching holes, upsetting metal for bolt heads, and similar operations. They should be made of soft steel.

131. Punches.—At b, Fig. 118, a plug punch is shown in position on the metal over a washer or bolster ready for punching. When properly located, a few blows of the hammer will force the punch through the metal and produce a smoothly finished hole.

Notice that the punch is made somewhat tapering, and that the heavier portion is driven through first. Precaution should be taken not to have the punch fit the bolster too closely or be too long, also to have it directly over the hole in the bolster before attempting to drive it through.

Holes can be punched with ordinary handle punches, but care should be taken not to have them too long; even then a bolster or something must be used, so that the punch can be driven clear through the metal and not come in contact with the lower hammer die.

132. Steam Hammer Work.—The following exercises are known as machine forgings. They will require the use of the steam or power hammer and the tools just described. It will be necessary to know beforehand what parts of the work are to be finished, so as to provide a proper allowance at those places. The term “finished” means that the surface is to be removed by the machinist, and the work made smooth and to the required dimensions.

All machine drawings should designate the parts that require finishing, by either the entire word or just the letter “F.” The symbol is more convenient to use for only certain parts, but if the entire forging is to be finished, it may be indicated by “finished all over.”

133. Crank Shaft.—Fig. 119. This is shown without dimensions or finish marks. Select stock sufficiently heavy to produce a forging equal to that shown at b.

Make two depressions with the checking tool, as shown, the distance c between them corresponding with the dimension a on the crank. Draw the ends square and straight on the lower side, as shown at d, then octagonal, and then round. In this way the fillets and shoulders will be equal, as shown at e. The two ends should be swaged smooth and round, then made perfectly straight and at right angles to the crank.

134. Connecting Rod.—Fig. 120. The volume of the material required for section e must first be estimated. Then ascertain how many inches of the selected material will be required to give this volume. This will be the distance b for the fullering shown at a. The sizes of the fullers to be used should be the same as the required radii r. Fuller in the depressions as shown, so that they will correspond with the dimensions g, h, and l of the finished rod. The metal between g and h should then be drawn slightly tapered, as shown in the top view, and to a uniform thickness l. The small end must now be drawn to the proper size and trimmed with the circular cutter. Make the rod perfectly straight, with the ends parallel to each other and to the rod.

135. Rod Strap.—Fig. 121. This forging is begun by blocking out, as shown at B, with e a little greater than h and plenty of stock at f. The length k must equal l, with a slight allowance of surplus metal for the bending operation.

Sketch C shows the method of bending. A forming block m should be provided for this, the width of which corresponds nearly with the dimension g, and the thickness is somewhat greater than that at d. The length may be equal to the inside length of the finished strap, but it could be used if shorter. By placing this block perpendicularly on the bottom die, with the forging resting on it and a small piece of metal n for a blocking on top of that, the upper die may be brought down and a full head of steam turned on while the stroke lever is held down. Both ends can be bent down simultaneously with sledges.

After the bending, there may be required more or less labor with the flatter and sledge to square it up in proper shape. Then the ends can be cut off to equal lengths with the hack or hot cutter.

136. Eccentric Jaw.—A, Fig. 122. First form the depression c with the checking tool; then draw out the end d to the form e and punch a hole at f by using an oblong punch.

Then using the hack, carefully cut from both sides at the places indicated by the broken lines at f. Any fin remaining after the cutting can be removed with a hot cutter or the trimming chisel. The ends forming the jaw can be drawn to the proper size by the use of the yoke. The semicircular ends can also be cut by using the circular cutter, but these ends will require some trimming with a hot cutter, because all the work must be done from exterior sides.

137. Hand Lever.—A, Fig. 123. This illustrates and explains a simple method of stamping which may be extended or adjusted to suit a variety of forgings.

In this case two stamping rings are made to suit the work at hand, as follows: If the dimension h is 2 inches and the thickness of the lever i is ¹/₂ inch, the rings must be made of ³/₄-inch round stock, and welded to an inside diameter corresponding with the dimension k.

First draw the material to correspond exactly with the dimension k in one direction and somewhat greater than that of h in the opposite. The latter dimension is made larger, to provide some excess metal for the stamping operation, which is done in the following manner: Place one of the rings centrally on the bottom die of the hammer, as shown at B; lay the material on this, with the dimension h perpendicular and the proper distance from the end to provide enough metal for forming the lever and handle. Then place the other ring on top of the material directly above the lower one, and deliver blows on these rings until the entire thickness almost corresponds with the desired dimension h. The rings will be forced into the metal and form two depressions, as shown at C. Next with a hot cutter or trimming chisel remove the metal forming the corners e. Then draw out the lever portion roughly, at first; by using the taper tool a uniform taper can be produced correctly. Cut off the extra stock at the boss, and remove the surplus metal which projects between the bosses as indicated at d, and finish the end smoothly with a common top swage. The handle portion can be formed at the anvil with top and bottom swages after the end has been cut semicircular and to the desired length.

138. Connecting Lever.—A, Fig. 124. After drawing the metal to an appropriate dimension, fuller two depressions b on opposite sides, the proper distance from the end, to form the jaw. A single boss c should be stamped with one ring, at the required distance from b to provide the necessary amount of metal for the length d of the lever. Then remove the corners, as indicated by the broken lines. Begin drawing the lever by using the combination set, and finish the flat side with the hammer, producing the taper edge with the taper tool. Punch a square hole in the jaw and remove the metal indicated by the broken lines at e, with a hot cutter. Finish the jaw similar to the eccentric jaw and the boss as in the previous exercise.

139. Solid Forged Ring.—Fig. 125. This should be made of soft steel, the dimensions being supplied by the instructor to suit the stock and equipment at hand. The volume (see calculating rules and tables, pp. 197-206) of the forging must first be determined and some surplus allowance for forging provided. The process of making the ring will be found in the explanation of the use of the yoke in section 129.

140. Double and Single Offsets.—Fig. 126. The following exercises are given to explain the use of simple appliances for producing work accurately and rapidly. Examples similar to the four following ones would require considerable care and skill if they were to be produced without the use of the steam hammer.

At a is shown a double offset bend, the depth of which, for illustration, may be ¹/₂ inch. To produce this, place two pieces of ¹/₂-inch flat material, with width corresponding to that of the material to be bent, on the lower die, and sufficiently far apart to allow the offsets to form between them. On these the material is placed, and on top of that also, located midway between the ¹/₂-inch supporting pieces, a third piece of ¹/₂-inch stock is placed. The width of this should correspond with the required dimension at a and should be somewhat longer than the width of the material to be bent. This arrangement is shown at c. By delivering a sufficiently heavy blow upon them, the two offsets, will be formed simultaneously and accurately.

In all operations of this kind the thickness of the lower forming pieces should always correspond with the required depth of the offset, and the corners should be ground round to prevent shearing or galling.

At d is shown a single offset which can be produced in a similar way, with the exception that here only two blocks are required. But the forming corners of these should also be ground as previously stated, and they are placed in position as shown at e.

Figure 127 shows the method of bending a semicircular pipe or rod clamp. Here a piece of round stock f is used above for stamping, but as the lower blocks are easily displaced, it would be advisable to make a stamping block like that shown at g. This could be used instead of the two lower pieces. If the clamps were to be made square, then the stamping block should be like the one shown at h, and the upper piece as at f should be made square.

Questions for Review