Modern Machine-Shop Practice Part 118

1683, and the latter operates a worm W, Fig. 1684, engaging a worm-wheel W, which drives the bevel gear _a_, shown by dotted circles in Fig.

1685; _a_ drives the bevel gear _c_ upon the sleeve _o_, which has journal bearing (in the frame A of the machine) both at its upper end and immediately above C. The upper end of the sleeve _o_ is threaded to receive an inner sleeve _n_, within which is a spindle _v_, having journal bearing at each end of _n_ and being fast to _m_, so as to revolve with it. End motion to _n_ is prevented by a collar at its upper end _r_ and by three steel washers at _i_, the latter taking the thread when the drill spindle _m_ is in operation. The inner sleeve _n_ is prevented from revolving by means of a lug or projection which pa.s.ses into a slot or groove running vertically in the bore of the outer casing A; hence when _o_ is revolved by _a_ it acts as a nut to _n_, causing the latter to move endways and feed the drill spindle _m_.

To enable the engagement or disengagement of the automatic feed, there is at F, Fig. 1684, a friction disk, the female half of which is fast upon the spindle that drives bevel gear _a_ in Fig. 1685, while the male half is in one piece with the hand wheel Z, Fig. 1684, which has journal bearing upon the spindle of _a_. G is a hand nut for engaging or disengaging the friction disks. In addition to the ordinary work table T, the knee U carries on a projection X a work-holding vice V, which is a great convenience, especially for cylindrical work. The base of the machine is provided with a plate upon which work may be secured independent of the work table T, or the lower end of a boring bar may be steadied by a step bolted to the base plate.

The construction of the machine, as will be seen, is very substantial throughout, since all the strains are central, the spindles are well supported, and there is a commendable absence of springs, pull-pins, and other light parts that are liable to get out of order from the wear and tear of the ordinary machine-shop tool. It may also be remarked that the combination of the two spindles is effected without impairing either the usefulness or handiness of the vertical spindle.

[Ill.u.s.tration: Fig. 1686.]

In Fig. 1686, which is taken from _Mechanics_, is ill.u.s.trated a combined drilling and turning machine. In this machine the motion for both drilling and turning is received by belt on the cone pulley shown on the right, which is provided with back gear similar to that of a lathe. The live spindle thus driven has a face plate at the left-hand end, whereon work may be chucked to be operated upon by a tool in the compound slide rest shown on the cylindrical column. Motion to the drill spindle is conveyed by belt from a pulley on this same live spindle, hence the same cone pulley and back gear are utilized for either drilling or turning.

The self-acting feed for the drill spindle is actuated by an eccentric on that spindle operating an arm, having a pawl engaging with the ratchet wheel on the lower end of the vertical feed spindle. Obviously when the pawl is thrown out of engagement with the ratchet wheel, the horizontal hand wheel may be used to feed the drill spindle by hand or to withdraw it, as the case may be.

The work table for drilling operations has motion laterally in two directions (one at a right angle to the other) by means of being carried on slides, and is fitted to a vertical slide on the face of the column so that it may be raised and lowered to suit the height of the work by means of the worm and worm-wheel shown, the latter being on the same shaft as a pinion engaging with a vertical rack on the face of the upright frame or column.

In Fig. 1687 is represented a horizontal drilling and boring machine. In this machine the work-holding table is provided with a hand feed, and the drilling or boring spindle with hand and self-acting feed, the latter being variable to suit different kinds of work. The table has a compound motion upon suitable slideways and rests upon a frame or knee that is elevated by two vertical screws that are operated by hand wheel.

This knee fits to a vertical slideway on the main frame, so that its upper face, and therefore the face also of the work table, is maintained parallel with the drill spindle at whatever height it may be set from it.

The arbor that carries the drill spindle is arranged with a face plate so that the machine can be used as a facing lathe. The feeds are arranged in two separate series, a fine and a coa.r.s.e, and both of these series are applicable to any speed or any size of drill. The value of the coa.r.s.e feed will be felt in all kinds of boring with bars and cutters, inasmuch as it is possible to rough out with a fine feed and finish with a light cut and a very coa.r.s.e feed.

For work that is too large to be conveniently lifted to the table of a machine the floor boring machine is employed.

Fig. 1688 represents a machine of this cla.s.s, which consists of two heads that may be moved about upon, and secured to, any part of its base or bed plate to which the work is secured. The boring bar it will be seen stands horizontal, and may be set at any height from the base plate between the limits of 14 inches and 6 feet 4 inches, the driving head being raised on its slideway on the face of its standard or column by automatic mechanism. The feed is automatic and variable in amount to suit the nature of the duty.

The bar has eight speeds, four in single and four in double gear.

In order to insure that the crank pins of locomotive driving wheels shall stand with their axes parallel to that of the wheel shaft, and that they shall also stand 90 apart when measured on the wheel circle, it is necessary that the holes for these pins be bored after the wheels are upon their shaft, it being found that if the crank pin holes are bored before the wheels are upon the shaft they are liable to be out of parallel and out of quarter.

[Ill.u.s.tration: Fig. 1690.]

To avoid these errors a quartering machine is employed, such as shown in Fig. 1689. This machine consists of two heads carrying stationary or dead centres to hold the wheel axle, as in a lathe. Each of these heads is provided with a boring bar having an automatic and adjustable feed, the axes of these bars being 90, or one quarter of a circle, apart.

As both crank pin holes are bored simultaneously and with the wheel rigidly fixed and held upon centres the work will obviously be true.

This machine may also be used as an ordinary horizontal boring machine.

[Ill.u.s.tration: Fig. 1691.]

Multiple drilling machines are employed for two general purposes: first, those in which a number of holes may be advantageously drilled simultaneously; and second, where a number of operations require to be performed upon one and the same hole. When the object is to drill a number of holes s.p.a.ced a certain distance apart in one piece of work, the spindles may be so constructed that their distances one from the other may be adjustable, so that they may be set to drill the holes equally or unequally s.p.a.ced as may be required.

In such machines it will be more convenient to feed the work to the drill, so as to have but one feed motion, instead of having a separate feed motion to each drill spindle. When, however, a number of separate operations are to be performed upon the same hole, it is preferable to rotate the table so that the work may be carried from one spindle to the other, the spindles feeding automatically and simultaneously.

Fig. 1690 represents a three-spindle drilling machine. The main driving spindle is vertical and within the top of the column, having three pulleys to connect by belt to the vertical drill driving spindles, whose driving pulleys are of different diameters to vary the speed to suit different diameters of drilling tools. A foot feed is provided by means of the treadle, and a hand feed by means of the lever, the weight of the work table being balanced by means of the ball weight shown. The work table is adjustable for height in a main table, that is adjustable for height on the face of the column. Similar machines are made with four or more spindles.

Fig. 1691 represents a four-spindle machine, in which each spindle has a separate and independent feed, which may be operated in unison or separately as may be required.

[Ill.u.s.tration: _VOL. I._ =EXAMPLES IN BORING MACHINERY.= _PLATE XXI._

Fig. 1687.

Fig. 1688.

Fig. 1689.]

The four spindles are driven by means of a gear-wheel engaging with a gear on the central or main driving spindle. The work-holding table rotates about the column of the machine, and is arranged with a stop motion that locks the table in position when the work-holding chucks are exactly in line with the drill spindles. Suppose, then, one spindle to drive a drill, the second driving an enlarging drill, a third driving a countersink, and a fourth a reamer. A piece of work may then be fastened beneath the first spindle and be drilled. The table may then be rotated one-fourth of a revolution, bringing it beneath the enlarging drill, while a second piece of work is placed beneath the first or piercing drill. The table may then be given another quarter rotation, bringing the piece of work first put in beneath the countersink, the second beneath the enlarging drill, while a third piece may be placed beneath the first or piercing drill. The table being again given one-quarter rotation the first piece will be brought beneath the reamer, the second beneath the countersink, the third beneath the enlarging drill, and a fourth may be placed beneath the piercing drill; all that will then be necessary is to remove the first piece when it arrives at the piercing drill and insert a new piece; the four spindles operating simultaneously, and the process continuing, the four operations proceed together.

Thus the piece of work is finished without being released from the holding devices, which insures truth while requiring a minimum of attendance. The amount of feed being equal for all four spindles the depth to which each tool will operate is gauged by the distance it stands down from the feeding head, each spindle being capable of independent adjustment in this respect, so that the tool requiring to move the farthest through the work will meet it the first, and so on.

[Ill.u.s.tration: Fig. 1692.]

Figs. 1692 and 1693 represent a combined drilling and turning machine for boiler-maker's use. The machine consists of two uprights or drill standards which can be traversed along horizontal slides on beds which are fixed at right angles one to the other. The work to be drilled is carried on a turntable or work-holding table, the pivot and carrying frame of which can be traversed along a third set of guides lying between the other two and forming an angle of 45 with either of them.

Thus, by adjusting the relative positions of the turntable and the drill standards (each of which carries two drills), either a large or a small boiler can be conveniently operated on. Worm-gear is provided for revolving the turntable, either to divide the pitch of the holes, or when the machine is used for turning the edges of f.l.a.n.g.ed plates, or for boring the large holes for flue tubes. Longitudinal seams may be drilled by laying the boiler horizontally on chucks alongside one of the beds, and traversing the drill standard from hole to hole.

Referring especially to Fig. 1693, A^{1} and A^{2} are the two wings of the bed plate, each being provided with [V]-slides to carry the uprights or standards B^{1}, B^{2}, on each of which is a drilling head C^{1}, C^{2}, these being each adjustable vertically on its respective standard by means of rack and pinion and hand wheels D^{1} and D^{2}. The heads are balanced so that the least possible exertion is sufficient to adjust them. The vertical standards B^{1} and B^{2} are provided at their bases with a gear wheel operated by means of pinions at G^{1}, G^{2}, so that they may be rotated upon the sliders E^{1} and E^{2}, by means of which they may be traversed along their respective bed slides. The drilling heads are composed of a slider on a vertical slide on the face of the vertical standard or upright, rotary motion and the feed being operated as follows: Power is applied to the machine through the cones K^{1} and K^{2}, working the horizontal and vertical shafts L^{1} and L^{2}, &c.

On the vertical shafts are fitted coa.r.s.e pitch worms sliding on feather keys, and carried with the heads C^{1} and C^{2}, &c. The worms gearing with the worm-wheels M^{1} and M^{2} are fitted on the sleeves of the steel spindles N^{1} and N^{2}. The spindles are fitted with self-acting motions O^{1} and O^{2}, which are easily thrown in and out of gear.

The sh.e.l.l to be drilled is placed upon the circular table H, which is carried by suitable framework adjustable by means of screw on the [V]-slide I, placed at an angle of 45 with the horizontal bed plates.

By this arrangement, when the table is moved along I it will approach to or recede from all the drills equally. J^{1} and J^{2} are girders forming additional bearings for the framework of the table. The bed plates and slides for the table are bolted and braced together, making the whole machine very firm and rigid.

The machine is also used for turning the edge of the f.l.a.n.g.es which some makers prefer to have on the end plates of marine boilers. The plates are very readily fixed to the circular table H, and the edge of the f.l.a.n.g.e trued up much quicker than by the ordinary means of chipping.

When the machine is used for this purpose, the cross beam P, which is removable, is fastened to the two upright brackets R^{1} and R^{2}. The cross beam is cast with [V]-slides at one side for a little more than half its length from one end, and on the opposite side for the same length, but from the opposite end. The [V]-slides are each fitted with a tool box S^{1} and S^{2}, having a screw adjustment for setting the tool to the depth of cut, and adjustable on the [V]-slides of the cross beam to the diameter of the plate to be turned. This arrangement of the machine is also used for cutting out the furnace mouths in the boiler ends. The plate is fastened to the circular table, the centre of the hole to be cut out being placed over the centre of table; one or both of the tool boxes may be used. There is sufficient s.p.a.ce between the upright brackets R^{1} and R^{2} to allow that section of a boiler end which contains the furnace mouths to revolve while the holes are being cut out; the plate belonging to the end of a boiler of the largest diameter that the machine will take in for drilling. The holes cut out will be from 2 ft. 3 in. diameter and upwards. Power for using the turntable is applied through the cone T. The bevel-wheels, worms, worm-wheels and pinions for driving the tables are of cast steel, which is necessary for the rough work of turning the f.l.a.n.g.es.

[Ill.u.s.tration: Fig. 1693.]

As to the practical results of using the machine, the drills are driven at a speed of 34 feet per minute at the cutting edges. A jet of soapsuds plays on each drill from an orifice 1/32 in. in diameter, and at a pressure of 60 lbs. per square inch. A joint composed of two 1-inch plates, and having holes 1-1/8 in. in diameter, can be drilled in about 2-1/2 minutes, and allowing about half a minute for adjusting the drill, each drill will do about 20 holes per hour. The machine is designed to stand any amount of work that the drills will bear. The time required for putting on the end of a boiler and turning the f.l.a.n.g.e thereon (say, 14 ft. diameter), is about 2-1/2 hours; much, however, depends on the state of the f.l.a.n.g.es, as sometimes they are very rough, while at others very little is necessary to true them up. The time required for putting on the plate containing the furnace mouths and cutting out three holes 2 ft. 6 in. in diameter, the plate being 1-1/8 inches thick, is three hours. Of course, if several boilers of one size are being made at the same time, the holes in two or more of these plates can be cut out at once. The machine is of such design that it can be placed with one of the horizontal bed plates (say A^{1}) parallel and close up to a wall of the boiler shop; and when the turning apparatus is being used, the vertical arm B^{2} can be swivelled half way round on its square box E^{2}, and used for drilling and tapping the stay holes in marine boiler ends after they are put together; of course sufficient room must be left between bed plate A^{2} and the wall of boiler shop parallel with it, to allow for reception of the boiler to be operated upon.

[Ill.u.s.tration: _VOL. I._ =BOILER-DRILLING MACHINERY.= _PLATE XXII._

Fig. 1694.

Fig. 1695.]

[Ill.u.s.tration: Fig. 1696.--CAR-WHEEL BORING MACHINE.]

[Ill.u.s.tration: Fig. 1697.--PULLEY-BORING MACHINE.]

[Ill.u.s.tration: Fig. 1698.--COMBINED DRILLING AND COTTER-DRILLING MACHINE.]

In Figs. 1694 and 1695 is represented a machine which is constructed for the drilling of sh.e.l.ls of steam boilers, to effect which the boiler is set upon a table, round which are placed four standards, each carrying a drilling head, so that four holes may be drilled simultaneously, and is provided with a dividing motion that enables the table to be revolved a certain distance, corresponding to and determining the pitch of the rivet holes.

It is capable of drilling locker sh.e.l.ls of any diameter between four and eight feet. The feed motion to each drill is driven from one source of power, but each drill is adjustable on its own account. The depth of feed is regulated by a patent detent lever which engages with the teeth of a ratchet wheel, till released therefrom by contact with the adjustable stop. The drill spindle is then instantly forced back by the spiral spring and the forward feed motion continues.

It is the duty of the attendant to turn his dividing apparatus handle the required distance for the next hole, directly the drills are withdrawn, the amount of clearance between the drill point and the boiler sh.e.l.l being such as to give him proper time for this purpose, but no more. Self-acting water jets to the drills, and reflectors to enable the operator to see each drill, will be provided, but were not in action at the time views of the machine were made.

With an ordinary boiler sh.e.l.l formed in three plates, the three drills work simultaneously, and the one movement of the dividing apparatus, of course, applies to all. If the object to be drilled be not divisible into multiples of three, any other divisions can be produced by the dividing gear, either one, two, or three drills being used, as the circ.u.mstances may permit. Two heads can be s.h.i.+fted round from the angle of 120, at which they are shown, to positions diametrically opposite, as may be desired, and the third can be used or disused as wished.

Vertical gauge rods are provided, duly marked out to the various pitches that may be needed for the vertical rows of holes, and the movement of the drill spindle saddles is so simple and steady that accurate adjustment can be made without the least difficulty. In the same way when the drill would, in its natural course, come in contact with one of the bolts by which the plates are held together, the attendant can run all the drills downwards a couple of inches or so, then turn the dividing apparatus two pitches instead of one, and on raising the three drills again he can continue the circular row as before. The entire control of the machine is governed by the attention of one man to two levers and the one dividing handle, which are all conveniently placed for the purpose.

In Fig. 1696 is represented a machine for boring car wheels. The chuck is driven by a crown gear operated beneath by a pinion on the cone spindle. The feed motion for the boring bar is operated from the small cone shown on the cone spindle, there being three rates of automatic feed, which are communicated to the bar by a worm and worm-wheel operating a spindle carrying a pinion in gear with a rack on the back of a boring bar.

The worm-wheel is provided with a friction disk operated by the small hand-wheel shown, to start and stop the automatic feed, the large hand-wheel operating the rack spindle direct, and therefore giving a rapid hand-feed or quick return motion for the boring bar. The boring bar is counterbalanced by a weight within the frame. On the side of the frame is a small crane for handing the car wheels.