Power Hammers and Their Uses.

Modified on 2017/10/19 21:53 by Joel Havens Categorized as Metalworking Machinery
<h3>BY OSCAR E. PERRIGO, M. E. </h3>


&nbsp &nbsp &nbsp The variety of uses to which a good power hammer may be put is limited only by the ingenuity, skill and ability of the man who handles it. There has never been a time when the manufacturers of power hammers have been so well prepared to supply a useful variety of designs, suitable for special classes of work, and those for general work, as at the present time. The reasons for this condition are quite obvious. The needs and uses of power hammers have been thoroughly studied and appreciated and the new designs made with special reference to these needs which have been observed by all the builders, while those who have been long in the business have had the benefit of years of experience, which is incorporated in the details of design and construction so as to properly adapt each type to the work it is expected to perform.

&nbsp &nbsp &nbsp Power hammers are built of several different types, each of which is designed with reference to its adaptability to certain classes of work, which may be done upon them somewhat more conveniently and perhaps economically than upon other types. Yet, when used by an expert and resourceful forge man a surprising variety of work may be done upon any of them. Power hammers may be classified as to the method of driving them: First, steam hammers, or those driven directly by steam, the steam cylinder being directly over the hammer proper, which is attached to the lower end of the piston rod and guided by suitable vertical slides, and operated by the forge man's assistant. Second, hammers operated by a belt, which usually runs constantly, and is rendered operative by a tightening pulley, or a clutch mechanism controlled by the foot of the operator.

&nbsp &nbsp &nbsp Steam hammers are generally divided into two classes by the form of design: First, single frame hammers, or those in which the mechanism is supported upon a single frame or column, and, second, double frame hammers, or those in which there is a supporting frame or column on each side, united by the cylinder casting above.

&nbsp &nbsp &nbsp Belt hammers are of three general types, according to their design and construction: First, helve hammers, in which the hammer proper is attached to the end of a helve or lever pivoted at the opposite end in a similar manner to that of its early prototype, the trip hammer. Second, the form called by some builders the “compact” hammer, on account of its compact form, and somewhat similar in appearance to the single frame steam hammer. Third, the drop hammer, which is designed on the pile driver principle of a hammer run up between suitable guides to a sufficient height to give the required blow, and then released and allowed to fall upon the work to be forged.

&nbsp &nbsp &nbsp In regard to the weight of the hammer proper, it varies all the way from 15 pounds for the smallest helve hammer to 25,000 pounds and upward for a large double frame steam hammer. Ordinarily helve hammers carry a head of 15 to 200 pounds, although modified forms carry heads weighing up to 500 pounds. Drop hammers, or as sometimes called, drop presses, carry hammers weighing from 50 to 2,000 pounds.


&nbsp &nbsp &nbsp There are some peculiarities of construction in each type of hammer. For instance, the blow of the drop hammer is a “dead” blow, due to the impact of the falling hammer as represented by its weight and the distance through which it falls. In the steam hammer the blow is elastic, the flexibility being due to the compressibility of the steam acting upon the piston. In the helve hammer this elasticity is obtained by means of rubber cushions, or by the use of helical, or by laminated steel springs, sometimes by a combination of two of these devices arranged in various ways by the different builders. Thus the forging of pieces in formed dies, as the popular drop forge dies, and similar work, the action of the drop press is quite appropriate, while for general forging the elastic blow is preferable and the most effective, and at the same time lessens the shocks and strains upon the machine and thus prolongs its life.
 
&nbsp &nbsp &nbsp Originally power hammers were used almost exclusively for heavy forgings possible with hand hammers and sledges, and in forging blooms or billets in the manufacture of wrought iron and steel. The early hammers for this work were of the “trip” type, operated by cams or tappets attached direct to a water wheel shaft and operating under the helve of the hammer if located between the fulcrum and the hammer head, and over it if placed at the end of the helve, beyond the fulcrum. These hammers were used at a very early date, probably long before the steam engine as we have it today. The typical steam hammer, with a vertical cylinder over the hammer and whose piston rod carries the hammer head on its lower end, is a comparatively modern device, having been invented by James Nasmyth in 1842.

&nbsp &nbsp &nbsp The great utility of the steam hammer and the economy of the helve hammer stimulated ingenious mechanics to devise other forms for general application to forging purposes. Formerly these hammers were comparatively large and expensive, and used principally in large shops for heavy forgings. As the development of design made them of more convenient form for general work their use has been very much extended until now some form of power hammer is in almost universal use in shops doing even a moderate amount of forging, considered either as to size, weight, or variety.

 &nbsp &nbsp &nbsp While those who make machine forging a part of their regular business have long been convinced of the utility, which were not efficiency and economy of the power hammer, there are many jobbing shops that have not as yet been brought to realize the practical value of such machines in their everyday business, and are using the old methods of hand hammer and sledge, and by this course expending an unnecessary amount upon their labor account, which might with much more profit and economy be applied to the purchase of a good power hammer, designed for the general forging work of a jobbing shop. Not only can a much smaller force of men be employed, but by the use of a good power hammer it is entirely practical to do the work in a fraction of the time that it is now done, but it is also nearly always possible to do better and more satisfactory work.

&nbsp &nbsp &nbsp As hammers are made as light as 15 pounds, a machine can be purchased quite suitable to light work if the majority of work is of this character. The writer has in mind a certain shop in which there was space for but three fires, and was operated on small machine forgings and general repair work, the proprietor of which purchased a steam hammer, together with a boiler and the necessary connections, and set them up rather as an experiment than from a firm conviction of the practical utility of such an addition to his small outfit. The result was that he found he could not only do his usual volume of work with two fires, thus reducing his force and labor expense one-third, but that he could do heavier forgings than before and was therefore enabled to accept many jobs that were formerly beyond his capacity. He could also turn out more work with his two fires than he formerly did with three. His additional capacity for handling work naturally gave him a considerable advantage over his competitors, which in a few months resulted in the lighting of his third fire, and the increase in his volume of work to double his former capacity.

&nbsp &nbsp &nbsp This man's venture came about through his visit to a nearby manufacturing establishment in whose forge shop there was but three fires, and in which a power hammer had been recently installed, much to the satisfaction of the foreman, who was turning out a largely increased output at a considerably reduced expense, demonstrating most conclusively the practical value of the power hammer.
&nbsp &nbsp &nbsp The ingenious methods by which this foreman increased his output are worth noticing. For instance, a lot of special bolts were to be headed up with hexagon heads. He made a rough pattern for half a die, of suitable dimensions, and had two castings made from it. These he set in the die block with a steel wedge to hold them together. Into the complete die thus formed he dropped the pieces cut to length and the top end properly heated, and with two or three blows the head was formed. The wedge was knocked out, releasing the two parts of the die, the headed-up bolt withdrawn, and the operation repeated. The process was rather crude, of course, but it answered the purpose and was three or four times faster than to head up these bolts by hand and with the aid of a helper. Later on, an adjustable support was arranged for the bottom end of the rod to rest upon and much work of this kind was done.

&nbsp &nbsp &nbsp Much work in rounding up different sizes was accomplished by means of cheap dies, the upper and lower halves being held in position by a half-inch rod, 3 feet long, bent U-shape, and the ends attached to each half of the die. Many similar tools can readily be made by the ingenious blacksmith who possesses a power hammer and however primitive they may be, they will be of great assistance in turning out work rapidly.

&nbsp &nbsp &nbsp These jobs were to a certain extent repetition work, which does not often come to the regular jobbing shop, yet which frequently could be taken up if the shop was prepared to handle it economically. But for general forging, welding, bending and similar work the power hammer is excellently well adapted and in shops running as few as two fires, will be found to be a money-maker as well as a labor-saver.

&nbsp &nbsp &nbsp When much work of large and awkward form but comparatively light weight is to be handled, one of the lighter helve hammers is advisable. It should be remembered that dies and swages of any desired form can be used, both in the hammer head and upon the anvil, and whether in a drop press, an upright or a helve hammer, they are all sufficiently accurate so that the upper and lower portions of a die or swage will always fit after being properly set and secured.

&nbsp &nbsp &nbsp One of the peculiarities of construction is that in the steam hammer, drop press and the upright hammer, the lower face of the hammer and the top of the anvil are always parallel, so that whatever the thickness of the dies or swages, or whatever may be the thickness of the stock being forged, its upper and under sides will always be parallel. The helve hammer swinging upon a fulcrum instead of rising exactly vertical, opens at a slight angle, the vertical height being somewhat less at the side of the anvil nearest the fulcrum. This increases, of course, the higher the hammer is raised. However, the fulcrum is placed at a sufficient distance away so that for the usual kinds of forging this slight deviation does not particularly affect the work. This condition is to be taken into consideration in selecting a hammer for a certain class of work, as for instance, drop forge or die work, which must be done with a hammer sliding between vertical guides.

&nbsp &nbsp &nbsp Proprietors have sometimes objected to purchasing a power hammer on account of the cost, or the supposed cost, of a foundation, having perhaps received erroneous information in reference to this matter. For a drop hammer the foundation may be made entirely of concrete or of a combination of concrete and timber. Concrete is readily made anywhere that cement and rock are available and timber work can be built up, even if it is necessary to square up small logs with an axe and bolt them together in the most primitive way. Solid concrete makes an excellent foundation and one that will not deteriorate, as in the case with timber when affected by damp earth. It will not burn out from sparks or hot pieces of metal when using the drop for hot forging. Such a foundation should be from 8 to 14 feet deep, according to the size of the drop hammer.

&nbsp &nbsp &nbsp If timber is to be used the depth should be about the same and a concrete bed 12 to 24 inches deep should be put in. The timber work should be of from 8 by 8 to 12 by 12-inch Georgia pine timbers and long enough to reach a few inches above the ground. These should be securely fastened together in a mass a few inches larger than the base of the drop. They should be coated with hot tar or creosote before tamping the earth around them, so as to prevent decay. Holding-down bolts should extend down about half the length of the timbers.

 &nbsp &nbsp &nbsp For other forms of hammers the bedplate usually rests upon timbers supported on masonry or concrete piers, between which is a deeper foundation formed of closely cross piled and horizontally bolted timbers. Foundations should be of a depth and weight corresponding to the weight of the machine, the lighter ones only requiring a very simple and economical foundation, easily put in by the men in the shop if necessary.

&nbsp &nbsp &nbsp There are other good and labor-saving machines and appliances which have from time to time been designed and built for the use of the blacksmith and the machine forger, but it is a safe assertion to make that none of them possess the qualities of saving labor and increasing the output to the extent possible with a good power hammer, even in shops of quite moderate proportions.

<h3>Information Sources</h3>
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<ul>
<li> <cite>Southern Machinery,</cite>Nov 1908, pgs. 1 & 2</li>
</ul>
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