Modern Machine-Shop Practice Part 197

Fig. 2964 represents two views of the forgings, and it will be readily perceived that they are very difficult to make on account of the taper hole, which is shown in dotted lines. The first operation was to take a bar of steel 6-1/2 inches square and punch a hole, as at A Fig. 2965.

[Ill.u.s.tration: Fig. 2966.]

[Ill.u.s.tration: Fig. 2967.]

[Ill.u.s.tration: Fig. 2968.]

Next the piece was fullered at B, C by the fuller A, Fig. 2966, and cut partly off as at D. The fullering at B was then extended by a spreading fuller, shaped as at B, and the end E was drawn out. Then the piece was cut off at D. Next the spreading fuller was applied to C, and the forging appeared as in Fig. 2967. The end F was then drawn out, and the appearance was as in Fig. 2968.

[Ill.u.s.tration: Fig. 2969.]

The next operation was to enlarge the hole A, Fig. 2965, by drawing taper mandrels through it, the mandrels being about 7 in. long, having 1/2-in. tapes on them, and being successively larger. With the last of these mandrels in the hole the hub was drawn out to length and diameter, leaving the forging roughly shaped, but having the form shown in Fig.

2969.

[Ill.u.s.tration: Fig. 2970.]

To finish the hole the forging was then placed in a block such as shown at G, in Fig. 2970, a finis.h.i.+ng punch being shown at H in the figure.

[Ill.u.s.tration: Fig. 2971.]

The next operation was to let the steam hammer down upon the face of the punch and bring up the wings E F parallel, but not more than parallel, as then the mandrel could not be got out; the forging then appearing as in Fig. 2971.

The next process was to put in a bar mandrel such as shown in Fig. 2972 at I, the pieces J, K fitting on their sides to the mandrel and being curved outside to the circular and taper shape of the hole. The wings E F may then be closed on the mandrel to their proper width and the whole hub end being trimmed by hand, all the previous work having been done under the steam hammer. The hub being finished the key M may be taken out and the washer L taken off, when I can be pulled out, leaving J K to be taken out separately. A pair of tongs are then put through the finished hub end, while the wings are punched and trimmed under the steam hammer, and subsequently finished by hand.

[Ill.u.s.tration: Fig. 2972.]

[Ill.u.s.tration: Fig. 2973.]

[Ill.u.s.tration: Fig. 2974.]

The forging of wrought-iron wheels for locomotives is an excellent example. The spokes are first forged in two pieces, as 1 and 2 in Fig.

2973, and then welded to form the complete spoke. Piece 1 is first forged in dies under the steam hammer to the form shown in Fig. 2974, the dimensions being correct when the faces of the dies meet. The stud C D is then drawn out to the required length and dimensions.

[Ill.u.s.tration: Fig. 2975.]

[Ill.u.s.tration: Fig. 2976.]

[Ill.u.s.tration: Fig. 2977.]

[Ill.u.s.tration: Fig. 2978.]

The upper half of the spoke is first blocked out under dies to the shape shown in Fig. 2975, and the block B spread so as to form a section of the wheel rim, as shown in Fig. 2976, in which D is a die, L a movable piece wedged up by the wedges W W, and removable to enable the extraction of the forging, and F is an end view of the fuller, the use of which is necessary to cause the metal to spread sufficiently in the direction of the dotted lines. The corners of the rim are then cut off, as shown in Fig. 2973, and the rim is bent in a block having its top face of the necessary curve, as in Fig. 2977, A being the block, and B a piece movable, to allow the extraction of the work, and fastened in place by the key or keys C. The two pieces are then welded together, their lengths, &c., being gauged by a sheet-iron template, formed as in Fig. 2978. The welding is usually performed with sledge-hammers, but as soon as the pieces will hold well together, the drawing down is done under a steam hammer.

[Ill.u.s.tration: Fig. 2979.]

The spokes thus forged are then put together, as in Fig. 2979, B representing a wrought-iron band, encircling the rim of the wheel and closed upon the same by the bolt and nut at N.

[Ill.u.s.tration: Fig. 2980.]

Two washers are then forged, to be placed and welded in as at W W, in Fig. 2980.

The welding together of the spokes and of the washers to the spokes proceeds simultaneously. The washers are heated to come to a welding heat at the same time as the wheel hub is at a welding heat, and the two are welded together under a steam hammer. During the heating of the wheel hub, however, the band B, Fig. 2979, is tightened up with the screw to bring the spokes into closer contact when heated to the welding point.

[Ill.u.s.tration: Fig. 2981.]

[Ill.u.s.tration: Fig. 2982.]

The seams between the spokes at the circ.u.mference of the hub are welded with bars as shown in Fig. 2981, in which R R are two bars of iron which are operated by hand as rams. The wedge shape of the washers on their inside faces performs important duty in spreading the metal as well as simply compressing it, giving a much more sound weld than a flat washer or plain dish would.

The rim of the wheel is welded up as follows:

In Fig. 2982 are shown four spokes of the rim as they appear after the hub is welded. Into the [V] s.p.a.ces, as _a_, _b_, _c_, _d_; wedges of metal, of the form shown at E, are welded, after which the surplus metal of E is cut away, and the rim is solid as at F. In this process, however, it is necessary to weld all the pieces on one side of the wheel, as at _a_ _b_, &c., except one, which must be left unwelded until all the pieces save one on the other side are welded, and the wheel must be allowed to become quite cool before these last two pieces are welded.

Otherwise the strain induced by the contraction of the wheel rim while cooling will often cause the rim to break with a report as loud as that of a rifle. In those cases in which this breakage does not occur the wheel will be very apt to break at some part of the rim, when subjected to heavy shocks or jars.

The Figs. 2983 to 2999 (which are taken from _Mechanics_), ill.u.s.trate the method employed to forge the rudder frame of the steams.h.i.+p _Pilgrim_.

[Ill.u.s.tration: Fig. 2983.]

A side elevation of the rudder frame is shown in Fig. 2983.

The forging is made in eight separate pieces, which are so united as to make three pieces. These three pieces are finally joined by five welds.

The whole length being 29 feet 11-3/4 inches, and the weight 6,500 pounds.

[Ill.u.s.tration: Fig. 2984.]

[Ill.u.s.tration: Fig. 2985.]

[Ill.u.s.tration: Fig. 2986.]

[Ill.u.s.tration: Fig. 2987.]

[Ill.u.s.tration: Fig. 2988.]

[Ill.u.s.tration: Fig. 2989.]

The work is commenced by piling and welding on the porter-bar at the point in the shaft marked A. The stubs B and C having been previously prepared, the pile on the porter-bar is heated and welded up and drawn, shown in Fig. 2984, and scarfed as shown in Fig. 2985; the piece, shown in Fig. 2986, is then laid in the scarf and welded; then the part from B to A is finished to size, the finished forging of the post being shown in Fig. 2984. The surplus stock to the right of B, Fig. 2984, is worked down into the post E, and the distance from B to F is thus made correct without loss of stock or time. The curve at D, Fig. 2983, was worked down somewhere near, and then another pile and weld carries the job to G. Here the same operations as at first are repeated, and the arm C is welded in. There is left a good lump of stock in front of C, and by another pile and weld enough is added to make the job to I, as shown in Fig. 2987. Holes are then punched at J and L, and the piece of stock M cut entirely out. A cut is made to L with a hack opening out the piece N from the shaft. A taper punch, with a 3-inch point and a 4-inch head, is then driven at L; to throw the piece N out into the position shown at N^{1}, Fig. 2983; N^{1} is then finished, and the post from L to J brought to forging size; then, by the ordinary process of piling, welding and drawing, the shaft is finished from I to O. Next the porter-bar is cut off, so as to leave stock enough to make the lower part of the shaft, as shown in Fig. 2988. A hole was punched at Q, and the stubs drawn out, as shown in Fig. 2989, which gives the post complete.

[Ill.u.s.tration: Fig. 2990.]

The pieces S and T, and the tiller V, having been forged, as shown in Fig. 2991, the upper member of the frame is started on the porter-bar at W, Fig. 2983, and filed, welded and drawn to make the job as far as X^{1}. Wooden templates, such as in Fig. 2992, are provided for the pieces of the frame, the first extending from W to X^{1} and X, and the second including the part from X^{1} to X^{2} and X^{3}. After W, X^{1} has been drawn out with lumps left where the tiller and the arm S are to be joined, the scarf is made for the tiller and that is welded in, and the job finished to piece S. The scarf for S is then made, and S welded in. This makes the upper member of the frame. The lower member is made in the same way, starting at X^{3}. These two members are shown complete in Fig. 2993. The post, Fig. 2989, was sent to the machine shop, and was turned, planed, bored, and slotted, as shown in Fig. 2990. The frame was now ready to be pieced up, by welds at W, X, X^{1}, X^{2}, and X^{3}, Fig. 2983.

[Ill.u.s.tration: Fig. 2991.]

[Ill.u.s.tration: Fig. 2992.]

[Ill.u.s.tration: Fig. 2993.]

[Ill.u.s.tration: Fig. 2994.]