US2057778A

US2057778A - Balancing machine

Info

Publication number: US2057778A
Application number: US617825A
Authority: US
Inventors: Edward S Huff
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1932-06-17
Filing date: 1932-06-17
Publication date: 1936-10-20
Anticipated expiration: 1953-10-20

Description

ct. 20, 193%. E. s. HUFF BALANCING MACHINE 8 Sheets-Sheet 1 Filed June 17, 1952 INVENTOR.

ATTORNEY.

at 26, 19%. E. s. HUFF 2,057,778

BALANCING MACHINE Filed June 17, 1932 8 Sheets-Sheet 2 IN VEN TOR.

ATTORNEY.

Oct. 20, 1936. E. s. HUFF 2,057,778

BALANCING MACHINE Filed June 17, 1932 8 Sheets-Sheet 3 INVENTOR ATTORNEY.

Ct. 29, E. S. HUFF BALANC ING MACHINE Filed June 17, 1932 8 Sheets-Sheet 4 ATTORNEY.

Oct. 20, 1936. E. s. HUFF 2,057,778

BALANCING MACHINE INVENTOR.

ATTORNEY.

Oct. 20, 1936. v E s, HUFF 2,057,778

I BALANCING MACHINE Filed June 17, 1932 8 Sheets-Sheet 6 ATTORNEY.

' BALANCING-MACHINE Filed June 17, 1932 8 Sheets-Sheet 7 ATTORNEY.

Get. 20, 193% E s, HUFF 2,057,778

BALANCING MACHINE Filed June 17, 1932 8 Sheets-Sheet 8 :360 350 300 E70 240 5/0 /60 I50 /Z0 90 60 30 0 ATTORNEY.

Patented Oct. 20, 1936 PATENT OFFICE- BALANCING MACHINE Edward s. Hull, Dea rborn, Mich., assignor to Ford Motor Company, Dearborn, Mich a corporation of Delaware Application June 17, 1932, Serial No. 61'l,825

The object of my invention 'is to provide a device of the type known as a dynamic balancing machine whereby bodiessubject to rotation may be placed in running balance. It will be understood that all solid rotating bodies may be placed in static balance and still be out of dynamic balance when rotated, the effect of such unbalance being that the centrifugal force of statically,balanced portions when not axially aligned tends to rotate the axis of the body around some point thereon so that each end describes 1 a circular path. When a body is placed in dynamic balance the axis of the body and the rotating axis coincide so that no external force need be applied to retain the body in its bearings. The advantage of such balancing when applied to internal-combustion engine crankshafts is that the unbalance which otherwise tends to oscillate the respective ends of the engine is eliminated.

There are two methods of dynamically balancing bodies, one being where weights of material equal to an overbalance are removed from the body exactly at the point of :unbalance so as to place each increment or radial section of v the body in static balance: The advantage of) such method is that the body is not only relieved from all tendency to rotate ongany axis other than its normal axis but is also relieved from all stresses set up within the body. Obviously, engine crankshafts cannot be balanced in this manner and it is not required that they be' for the reason that to transmit the torsional crank loads and bending loads of the engine, the shaft must be of suilicient rigidity that it will more than resist the maximum internal stresses which might be set up due to other methods of balancing},

Consequently, the machine herein described is designed to balanceby another method wherein the unbalance of the shaft is not directly removed but rather wherein the effect of the unbalance on each endof the shaft is compensated or by the removal of a proportionate amount of metal from flanges on each end of the shaft. Although internal bending stresses are set up in the shaft as 'a' result, they are not sufficient to cause any measurable deflection and, of course, do not tend to vibrate the engine in which the shaft is used.

No attempt is made to provide a machine which .will directly ascertain the amount, angularity and axialposition of an unbalance in the body, the sole purpose of the device being to show the effect of such unbalance on the respective ends j of the shaft and to compute the amount and angularity of the metal which must be removed from the respective ends of the shaft to exactly i 13 Claims. (01. 13 -51) quent calculations based upon the readings of the machine, learn the exact amount and position of the unbalance but as this information would be of no value in balancing the shaft by this method no provision is made herein for directly obtaining the figure. I

In general, my machine comprises means for horizontally rotating the shaft at a predetermined constant speed while each end thereof is supported upon suitable spaced bearings. These supports are constructed to permit transverse movement relative to the shaft axis and to permit pivotal movement of the shaft around vertical centers which pass through the shaft flanges from which the metal is to be removed. In operation one of the supports is held from transverse movement and the amplitude of movement of the'other end obtained. This amplitude is the resultant of the unbalance at the exact axial position of the flange. The other end is likewise balanced. The angularity is also ascertained so that it is only necessary to remove the amount of metal shown from each flange to balance the shaft. The novel feature of this construction is the means for pivoting'the shaft on pivots passing through the centers of the drilling flanges so that the machine may be calibrated to read directly in inch ounces, making the use of slide rules and otherlike devices unnecessary.

Still a further object of my invention is to provide a machine of the class described wherein an extremely high degree of accuracy is obtained,

this accuracy resulting partly from the novel method of reading the device.v This method might possibly be termed a nullifying method in that the unbalance of the work causes movement vice is unique in that I provide micrometer adjustments whereby the positions'of the indicator may be shifted back to a zero position, or that which it assumes when a perfectly balanced shaft is tested. It will be apparent that a much more accurate reading can be obtained by bringing the indicator back to a fixed cross hair on a scale and reading by a micrometer the amount of movement required to accomplish this than is possible by directly reading the amount such indicator shows by ruling the screen upon which it is impressed.

There are other features of this machine which contribute to the accuracy and high-speed characteristics thereof, however, even though the speed obtainable with this machine is about six times as fast as any balancer known to the applicant, still it shouldbe stressed that the increased speed of operation is not obtained at the expense of accuracy but is the result of the principle of operation and the fact that not a single operation is what has usually been called a cut and try operation. It should be kept in mind that this machine is theoretically correct in its calculations wherein it differs from most dynamic balancers where only an approximation is obtained. Further, the machine eliminating all computation from the operator is adapted for use with unskilled labor, there being no mathe- ,matics, slide rules, calculating charts or other devices required for use therewith.

It may be mentioned that the operator of the machine simply lays the shaft on open bearing supports, inserts a driving head, starts the motor, and moves two dials a portion of a revolution each to bring an indicating .line to a zero point on a scale, and then reads the graduations on the two dials, one of these figures being the inchounces of the unbalance and the other being the angular position in degrees of this unbalance.

The simplicity of this whole operation has been mentioned to show that the increased speed of production obtained withthis machine is not obtained'at the sacrifice of accuracy but rather results from the elimination of all calculations by the operator.

Other novel features will be described in the course of this specification, the most important of these features being the inverted pendulum type of support for the shaft, the novel electric dampener, and the tuning system whereby unbalances heretofore impossible to detect are'accurately measured with a minimum of time.

With these and other objects in view my invention consists in the arrangement, construction and combination of the various parts of my improved device, as described in the specification. claimed in my claims, and illustrated in the accompanying drawings, in which: 7

Figure 1 showsa front elevation. of a preferred form of my improved balancing machine.

Figure 2 shows a plan view of the machine:

. shown in Figure 1.

Figure 3 shows a sectional view, taken on the line 3-3 of Figure 1.

Figure 4 shows a sectional view, taken on the line 4-4 of Figure 3.

Figure 5 shows a sectional view, taken on the line.5-5 of Figure 2.

Figure 6 shows a sectional view, taken on the line 6-.6 of Figure 3.

the optical indicating system used in machine.

Figure 14 is a diagrammatic view, illustrating an ordinary oscillographed chart and sine wave showing the departures therefrom which are incorporated in this machine.

Figure 15 is a diagrammatic view, illustrating the mechanical amplifying system whereby transverse movements of the work supporting methis chanism will be mechanically amplified prior to the optical magnification thereof.

Figure 16 is a diagrammatic view of a crankshaft mounted upon the machines supports, illustrating the alignment of drilling flanges with the pivotal points of the machine, and

Figure 17 is a plan view, showing an arrangement of four of my machines whereby the operating labor cost per machine may be reduced substantially in half over that required for the operation of a single machine.

Referring to the drawings, I have provided a relatively heavy box shaped cast iron frame [5 having doors l6 disposed in the front and back thereof and in each end thereof and having a top plate i'l securely fastened in place by means of bolts iii. The purpose of constructing the device in such massive proportions is so that even slight vibrations of the device will be avoided. Inasmuch as an amplification of about 1500 times is provided in this machine, the necessity of having a rigid structure for supporting the mechanism can better be appreciated.

The crankshaft I0 is rotatably mounted in'a pair of supports l9 which coact with the bearings I4 thereby forming a cradle for rotation of the shaft about its axis. These supports l9 are free to vibrate in a path transverse to the axis of the crankshaft so that a universal drive is provided for rotating the crankshaft. To' rotate the crankshaft a synchronous'motor 20 is fixedly mounted upon the top of the'base plate IT, this motor being provided with an armature 2| fixedly. secured to a' tubular armature shaft 22, which shaft extends out from each end of the motor. The rear extending end of the shaft 22 is secured to one member of a universal joint 23, illustrated in Figure-8, the inner member of this joint being splined at 24. It will be noted that ball bearings are used exclusively in this joint as it is imperative that the frictional resistance in the joint be a minimum and constant. The motor 20 drives through the joint 23 and rotates a splined shaft 25 which is reciprocally mounted in the splines 24 and extends back through the tubular armature shaft "22. There is, however, considerable clearance between the shaft 25 and the bore in the tube 22 so that the free end of the shaft 25 may be movedout of alignment with the axis of the motor without appreciably affect- "a fiat spring 3B, this key being adapted to iit into a keyway machined in the crankshaft whereby the timing gear is secured on'the crankshaft. Inasmuch as the keyway in the crankshaft is always in a definite position relativeto pushed down over its end and then rotated until the key snaps into place. When the balancing is completed the chuck is moved toward the right, the shaft 25 sliding in the splines 24, so that the crankshaft may be lifted from the supports I9. The flexing of the diaphragm 26 compensates for the axial angularity between the crankshaft and the shaft 25, due to the reciprocation of the supports. It will further be noted that the discs 21 coact with an enlarged end on the shaft 25 so that excessive angular movement of the device is prevented thereby protecting the diaphragm 26 against breakage in case the crankshaft is accidentally dropped upon the chuck. V

It will be noted that a shaft 3| extends transversely across the machine. A switch mechanism or controller 32 is disposed within the body of the machine so as to be connected to this shaft. and knobs 33 are provided on each end of the shaft 3| so that the switch may be operated from either sideof the machine. The switch 32 is connected through suitablewirlng and relays, whereby the metor may be started and stopped from either side of the machine. The purpose of this arrangement is so that one man, stationed at the rear of the machine, may set the crankshaft in place and connect the driving chuck therewith, this man operating the knob on his side of the machine to start the motor and another man,

I located at the front of'the machine, may then take readings from certain dials on the machine and when these readings are completed he then stops the motor by means of the knob 33 on'his side of the machine. Certain markings are then placed on the shaft and the operator in the rear of the machine then removes same and-installs another one in its place.

It is extremely important that the motor 20 be. capable of operation at a constant speed and to obtain such constant speed a novel synchronous motor is provided. This motor is designed to operate exactly at 600 R. P. M., from time corrected alternating current. Further, it is desirable to provide a brake on the motor so that the crankshaft or work being balanced may be stopped in a minimum time after the readings are taken. A novel electric brake mechanism is provided which consists essentially of means for reversing the current inthe motor, this reversed current being controlled by the direction of rotation of the armature. Both the brake mechanism and motor construction will be described in another application as such construction does not'directly bear upon the machine described herein. 1

Referring now to the mechanism for supporting the crankshaft in position, Figures 5, 15 and 16 illustrate the construction. The frame is provided with a dovetailed way 34 which extends substantially the length thereof adjacent to its'rear wall and a pair of carriages 35 are reciprocally mounted in these ways so that these carriages may be positioned in any place along the way to adapt the machine to various lengths of crankshafts. Each of these carriages 35 has a pair of major truss members 36 secured thereto, these truss members being resiliently secured to i the front and rear faces thereof in position to extend upwardly in a vertical direction. Spring steel truss member.

- movement around the carriage.

strips 31 form the connecting link between the base of the truss members and the carriage, these strips having one edge rigidly secured to the car riage while the other edge is rigidly sec'uredto the Thus, the upper ends of these truss members are free for a limited oscillating The upper ends of each pair of truss members are likewise resiliently secured to a fulcrum plate 38 by a second pair of spring steel strips 39, the plate 38 having an extension 40 formed integrally therewith which extends down between the trusses to a position adjacent to the carriage 35. From the foregoing it will be seen that the plate 38 and extension 40 may reciprocate in a transverse plane through a limited movement and that the mounted, the" lower end of the shaft being secured by means of a conventional ball bearing 42 while the upper end of the shaftis rotatably mounted by means of three ball bearing rollers spaced therearound. As will be noted from Figure 5, two of these ball bearing rollers are pivotally mounted in the plate 38 while the third roller is mounted upon an eccentricshaft 43 so that upon rotation of this shaft the bearing may be moved radially toward or from the shaft. Thus a very close fit may be maintained between the upper end of the shaft 4| and the plate 38. This is an important feature as even a slight play between the shaft and plate will cause inaccuracies in the readings of the machine.

From Figure 16 it will be seen that the upper ends of the shafts 4| are connected directly to the supports l9 and that these supports are offset in opposite directions so that the axes of the shafts will be aligned with the centers of the flanges I3. The center distance between the shafts 4| is adjusted to exactly equal the distance between the flanges d3 of the crankshaft to be balanced. .This one provision makes it possible to provide a direct reading machine and eliminates all calculations by the operator.

Inasmuch as only one end of the shaft is measured at a time means are provided whereby the plates 38 may be selectively and rigidly held against transverse movement. To accomplish this a solenoid operated clamping device is provided, as shown in Figure 10, for each of the plates 38 so that upon actuation of either solenoid the adjacent plate 38 will be held rigidly with the frame of the machine. The upper portion of each extension 40 is provided with a pair of spaced blocks 44, each of which has a vertically extending y-groove therein. A pair of arms 45 are resiliently secured to the frame |5 by means of spring steel strips 46, the free ends of each of these arms being of V-shape so as to engage the aforementioned V-shaped grooves in As will be seen from Figure 15, the crankshaft support is substantially an inverted pendulum and is subjectto the same laws in relation to its movement. As the natural period of oscillation of a pendulum of this length is relatively slow and as it is desirable to rotate the crankshaft quite rapidly in order that small unbalances may be detected, auxiliary means are provided for increasing the natural period c! vibration of the support to a point just. above the frequency resulting from the rotation of the shaft. This is termed the tuning of. the system herein. The crankshaft is rotated at exactly 600 R. P. M. and the natural period of vibration of the support adjusted to a point only slightly above this figure.

If these two figures were made to coincide then resistance is offered to movement. -The amountof resistance can-be accurately adjusted so that only slight unbalances will cause a proportional reaction of the support.

of operation the more sensitive the machine becomes and the smaller itsrange becomes. For

automobile enginecrankshafts the applicanthas.

found that a 10 inch-ounce range is sufficient giving an-accuracy of less than one-tenth of an inch-ounce variation. I

In order to secure this tuning, adjustable flat springs extend between the lowerend of each extension 40 and the frame I5. There are four flat springs 48 required for each carriage, extending side by side in a horizontal direction. The intermediate portions of the center two springs are clamped to the opposite sides of the extension 40, while each end of these two springs is clamped bymeans of adjustable clamps 49 to the ends of the two outer springs. this outer pair of springs are clamped to adjusting screws 50 which are reciprocally mounted in a pair of brackets 5 I, these brackets being formed integrally with and extending upwardly from each side of each carriage '35. The adjusting screws'50 are provided with suitable nuts threaded thereon whereby upon tightening these nuts the center portions of the outerpair of leaf springs may be drawn away. from each other to thereby stress these springs to anydesired extent. The lower end of the extension 40 being secured to the intermediate portion of the center pair of I springs is free to'vibrate by flexing the springs.

In order to transmit this vibration to an indicating device a beam 52 is fixedly secured to each extreme lower end of the extensions 40, these beams. extending lengthwise of the machine and I having bars 53 secured to each end thereofwhich.

project toward the center of the machine. The

ends of each pair of bars 53 are connected by a rod 54. It will be apparent'from the foregoing that regardless of the position of either of the carriages in the'way 34, makingcontact with the rods 54in any place along their length will transfer the vibration of the support directly to the device making contact. The purpose of providing such rods is so that adjustment of the" carriages for the various lengths of crankshafts will not require the readjustmentpf any other part of the machine. i

It is verv desirable to mechanically amplify the Obviously,

The closer the natural. period of oscillation approaches the frequency The center portions of amplitude of vibration of the crankshaft supports because of the micrometer means for measurin this amplitude.

were provided then an extremely delicate meas-' 'uring device would be required while if the move- If no mechanical amplification which is rigidly secured to the baseof the frame.

I5. Spring strips 5'! form the connecting link between thelower portion of the minor trusses 55 and the brackets 56 so that the upper ends of these trusses are free for transverse oscillation. A minor fulcrum plate 58 connects each pairof upper ends of the trusses 55through still more spring strips sothat upon oscillation of either of the trusses 55 the connecting plate 58 is reciprocated transversely. An arm 59 extends downwardly from each plate 58, the lower end of which comprises what will be termed a tar'getiil. This target is provided with a verticalslotted opening therein this slot being about of an inch long and .005 of an inch in width. A bracket 5| connects each of the lower portions of the inner minor truss members with the adjacent rod member 54, whereby transverse vibration of the rods 54 will be transmitted to the lower portion of the adjacent minor truss member and cause oscillation of same. 1

The foregoing mechanism constitutes an essential part of this machine, it being the mechanical amplification system whereby a slight lateral movement of the supports ill will be converted into considerably larger transverse movement of.

most support causes approximately eight times the transverse movement on the minor plate 58. As the target 50 is integral with the plate 58 and remains perpendicular to the base of the machine it follows that the target will likewise be moved through approximately eight times the range of the support l9. Consequently,; measuring the amplitude of movement of vthe target will be a measure of the amount or resultant of the unbalance at the end of the shaft being measured. It has been found that some means must be provided for dampeningthe movement of the target when the machine is adjusted for sensitive readings, as slight vibrations in the trusses themselves tend to alter "the harmonio motion theoretically described by the target. The movement of the target should be harmonic and when this movement is visually indicated and optically am- I plifled, it should appear as a sine wave form, the

degree of the wave being synchronized with the crankshaft. However, due to vibrations in the supports themselves, ripples occur on the wave front which prevent accuratereading of the position of the wave peaks. The purpose of the dampener, about to bedescribed, is to iron-or smooth out these ripples and thus allow a close reading of the sine wave'curve.

Figures 4 and 5v illustrate the construction of this dampener from which it will be noted that I have provided a pair of fairly strong magnetic fields, each disposed above one of the minor plates 58. Each of these magnetic fields is produced by a core 62 having an air gap about of an inch therein in which a copper plate 63 is disposed so as to cut the lines of force across the air gap. Suitable windings 64 are provided around the core 62 so that when these windings are energized, a strong flux density will be impressed across the air gap. The ends of the plate 63 are fastened to the'plate 58 so that transverse vibration of the target mechanism vibrates theplate 63 in the airgap. I

As is well known cutting the lines of force of a magnetic field is resisted in' direct proportion to the speed of the member doing the cutting and that a, lag will result in the indicating system due to this resistance. Of course, this resistance will result in a smaller amplitude of movement of the target but this can be compensated for by lessening the tension on the tuning springs or by graduating the device to allow for the dampening. However, the lag produced by a dampener cannot be compensated for by simply altering the graduations andcan only be compensated for byany means if the lag is directly proportional to the speedof movement so as to produce a constant time element for the lag. An increased amplitude of the target-results in an increase in the cutting speed of the plate, the frequency remaining constant. of course, the increased cutting speed results in a directly proportionate increase in the movement lag but the speed increase is exactly sufficient to make the ,lag occupy a constant time interval over all ranges of movement. This constant time lag can only occur if the resistance of the dampener is' directly proportional to the speed of the cutting plate. r

The importance of this function of the dampener will be apparent when'it is remembered that for.

' 'dampener can be used the lag, unlikethe dampening, afiectsthe lateral position of the wave peak and as this lateral position is used to indicate the angular location of the unbalance in the shaft, the correction for lag must be made in the angular micrometer device. As the angular micrometer. must read over the same angular scale regardless of the amplitude of unbalance, it will be seen that a constant time lag is an essential requirement'if the device is to measure in a theoretically correct manner.

The foregoing has been explained in detail to distinguish the advantages of this dampener over other types of dampeners not having its characteristics. For example,'the resistance of a frictional dampe'ner is constant and consequently, its time lag will be less. than can be compensated for. The resistance of all fluid dampeners varies about as the square of the speed so that the time lag will be greater than can be compensated It is believed that only the applicants and still the dampening in such dampeners be correctly the full range of the inand lag inherent compensated for over strument.

Inasmuch as the lag produced by the dampening devices must be constant and as this lag depends upon the intensity of the magnetic field,

, it is found desirable to provide a voltmeter I05 in the dampener circuit and also a rheostat I06 so that operation of the rheostat will vary the current in the dampener.

The device which constitutes the projectionpart of the system or optical leverwill now be described. It may be well to mention at the outset that the applicant makes no claim to the general optical system for projecting a wave upon a transparent screen as the same has'been used traversing the targets 60 However, the length of for years in oscillographs for both visual and permanent recording of the functions of alternating currents. In such oscillographs the generator to be tested directly drives an eight-sided mirror and the current from the generator energizes a coil which vibrates a target. A light is transmitted through the target on to the rotating mirror, the target vibration being aligned with the axis of rotation of the mirror. Consequently, the lateral displacement of the beam is controlled by the rotation of the mirror while the vertical displacement is controlled by the vibrating target. The well known sine wave form or some variation thereof according to the generator output is thus projected upon the screen. The function of the generator for all angular positions of rotation is thus learned.

The same general device is used herein for asccrtaining the movement of the target 60 and its angular relation with the crankshaft which drives the rotating mirror. There is one departure however from the conventional system and that is the positioning of a special lens in the system whereby a more concentrated light beam results.

The specific parts which make up this system comprise a centrally located source of light 61 which is housed in a suitable compartment 68 in the intermediate portion of the bracket 56. A pair of condensing lens units 69 are mounted in. each side of this compartment and focus the light source upon the targets 60. It willbe ap-' parent that inasmuch as there are two targets with the light 61 placed therebetween, two condensing lenses, one in each side of the compartment 68, are required. I have also provided two telescopes 10 of about 300 power which are focused on the slot in the target 60. The light then goes through the telescopes and is reflected upwardly atright angles by means ,of small prisms H. -The slots in the targets being very small inwidth, the lateral spread of the light therefrom will be very little. the slot is about of an inch so that a fan shaped beam of light; as shown by dotted lines 12, is thrown from the prism II. If desired a very small round opening could have been provided in each target 60 instead of the slot but such a small opening, approximately .005 of an inch in diameter, would allow such a small amount of light therethrough that the magniflcation of this light by the telethe telescope which, as hasbeen stated, is reflected upwardly from the prism II in a vertical direction.

Intersecting each vertical fan'shaped beam of light, I have provided a special lens I3, convex in a longitudinal plane only, the lateral section therethrough being rectangular in shape. The light from prisms II is thus concentrated, these concentrated beams being intersected by a second pair of prisms 14 so as to be reflected back toward'the center of the machine.

Located directly above the light 61 near the top of the machine, I have provided an eightsided mirror 15 which lies in the'paths of the light beams from the prisms IL This mirror is mirror I5 revolves M; of a revolution thereby reflecting a portiontof the light beam from the prism 14 across an arouate path. Only one sideof the system is used at a time so that there is no interference from the two beams. A suitable arcuatescreen I6 is provided upon which the target slot is focused by the telescope. From the foregoing it will be seen that if upon rotation of the crankshaft the target 88 remains stationary, the mirror 15 will simply oscillate the beam of light in a straight path from one side of the screen 16 to the other. However, if the target is vibrating in time with the rotation then this transverse movement will be amplified optically by the telescope and caused to move from one end ,of the mirror axis to'the other, and back as the mirror rotates revolution. Consequently, a sine wave path will be described on the scale [6 by the light beam which would,- with an ordinary harmonic motion, pro duce a form as shown by line 11, in Figure 14.

- Each lateral position of the beam corresponds to a definite angular position of the crankshaft. Ofcourse, when the target is stationary only a straight line is projected across the screen and the angular position of the shaft cannot be known, however, when the shaft is out of balance the unbalance causes the target to vibrate which in turn. causesthe projected line to assume a waveform, the-peak of which corresponds, after allowing for thelag of the dampening device, to

the angular position of unbalance in the shaft. Consequently, the, screen may be ruled ofl longitudinally into degrees, 'as shown, and vertically into inch ounces, to ascertain the effective angular positionand amount of the unbalance at the flange portion of the crankshaft. I The applicant-does not provide such a'conventional ruled scale or employ this method of registering the amount and angularity of the unbalance, the foregoingvbeing described only to better picture the improved means or departures from the conventional whereby an accuracy many times that heretofore obtainable is inva-- riably secured with his'device. A micrometer system of indicating is provided but as this apparatus is partly built into the mirror drive, this latter construction will be first described.

The means for rotatably driving the mirror 15 from the crankshaft consists essentially of stand-- ard worm and worm wheel gears and connecting shafts. ,The inner end of the motor armature shaft 22 is provided with a worm machined thereon which meshes with a worm wheel secured to one endof a shaft l8, this shaft extending into a cover member 19 which is positioned over'the top front portion of the machine. A second shaft 88 is operatively driven through suitable spiral gears 8| from the shaft 18, the free end of the shaft" extending'across the axis of the mirror 15 at a point spaced just slightly therebelow.

Referring to Figure 3, the shaft 88 is provided with one of a pair of spiral gears 82 this gear meshing with the other spiral gear 82 which is fixedly secured to a mirror shaft 83. The shaft 83 is-rotatably mounted in a pair of spaced ball bearings 84 so that rotation of the shaft 88 will rotate the shaft 83 through the spiral gears 82. 'I'heoppositeend of the shaft 83 is tapered and an octagon shaped rotor is mounted thereon. A flat mirror issecured to each side of the octagon rotor 85 to form the eight-sided mirror 15. The

ball bearings 84 are reciprocally mounted in a suitable sleeve 81 formed in the cover 19 and due to the spiral teeth on the gear 82 reciprocation of the bearings 84, shaft 83, mirror 85 and gear 82 as a unit, will cause a relative advancement or retardation of the mirror in relation to its former position in time with the crankshaft. This retarding or advancing movement of the timing of this mirror is extremely important in connection with this device, as it forms the means whereby the angularity of the unbalanced weight is ascertained.

A relatively heavy spring 86 is provided in the 1 sleeve 81 which resiliently urges the aforementioned mirror, bearings, shaft and-gear towards the frontof the machine. In order to resist this spring movement, a ball thrust bearing 88 is disposed on the front end of the shaft 83 and coacts with the inner end of a screw threaded plunger 89 which is threaded into the forward face of the cover 18 in axial alignment with the shaft 83. Anindicating disc 98 is rotatably mounted on a suitable bearing on the forward face of this cover I9, which disc is rotatably-connected to the plunger 89 so that rotation of a knob 9| which is secured to the disc through one revolution will rotate both the disc and the plunger 89 one revolution, thereby advancing the plunger through a distanceequal to the lead of the screw thread thereon. The advancement of the plunger 89 moves the upper gear 82 relative to the lower gear 82 thereby causing-the mirror 15 to advance or retard in its relative position. The

several screw threads and angularity of .the gear teeth have been proportioned so that rotation of the disc 98 through one revolution will advance the mirror exactly M; of a turn from its former position. Y

Referring back to Figure 114, the purpose of the aforementioned mirror advancing mecha-- nism will be described. In this figure it will be seen that the ordinarymethodof reading the angularity of the wave peak is to count the number of degrees on the scale which most closely bisects the peak of the wave. Inasmuch as the peak of such wave is not a sharp point, it is very diflicult to judge from a scale, the size of the one illustrated, an angularity closer than about 10 degrees. On the scale shown the lines are 30 degrees apart. In order to increase the accuracy obtainable with this machine, the

applicant instead of reading the angular position of the wave peak, causes a relative-rotation of the mirror which advances the peak of the wave to a zero line. One can tell with great accuracy when the sides of a symmetrical form are symmetrically spaced about a center line so that a very accurate location of the wave peak on each side of a center line can be accomplished. The

periphery of the disc 98 may thenbe calibrated to degrees and even minutes so that when the peak of the wave form is brought back to a center line or zero position, as shown by dotted lines I89 in Figure 14, the angularity through which the disc 98 has to be turned toaccomplish this may be readily read off with a fargreater accuracy than can be ascertained by reading the original position'of the wave peak on a ruled scale.

A suitable lamp bulb 92 is installed so as tograduated dials. It will be noted that each of to read in inch ounces.

proportions of the other parts of the device are I the telescopes 10 is fixedly secured in a bracket 93 which is pivotally secured at 94 on the bracket 56. This pivot is arranged to swing the telescope bodily in a substantially transverse path by the oscillation of the bracket 93. A suitable beam 95 is fixedly secured to the bracket 93 and one end of this beam has a compressed spring 96 associated therewith whereby the telescope is resiliently urged at all times to a position toward the rear of a machine. The other end of the beam 95 is formed having a segment shape and the lower end of a band H1 is fixedly secured to this segment saidband extending upwardly where it is secured to a segment shaped bracket 91 which is pivotally mounted in the upper portion of the machine directly above the telescope 10. The bracket 91 is rotatably mounted in the cover 19 and due to the spring 96 and band II1 pivotal movement of the bracket 91 however slight causes a similar pivotal movement of the beam 95 and telescope 10.

In order to oscillate wheel sector 98 mesh with a worm 99 formed on the end of a shaft I00, the shaft being rotatably mounted in the cover member 19. A suitable disc MI is nonrotatably secured to the outer end of the shaft I00, the periphery of the disc IOI being calibrated Theworm wheel 99 and the bracket 91 a worm soarranged that upon one rotation of the disc I'I the telescope is moved laterally through a distance equivalent to the lateral movement of the target 60 for the maximum range of the machine.

The function of this disc is that rotation thereof causes the relative position of the target and telescope to change so that the focus of the telescope, where formerly on the intermediate position assumed by the slot 60 when at rest, is now moved to focus on the slot at one end of its stroke. The efiect of this movement is to cause the wave peak to drop down to a zero position on the screen or that shown in Figure 14 by dotted lines'IIO. The exact amount of the movement of the disc IOI required to bring the peak of the wave down to a zero center line can be read much more accurately than the amount the wave peak is above the center line.

There are two reasons why such an accuracy can be effected, the first being that the peripheries of the discs IOI and 90 are approximately 20 and 30 inches, respectively, whereas the length and width of the largest screen which it is possible to use is only a fraction of these dimensions. The second and most important reason, however, is that the wave peak being shifted agrees with a pair of cross hairs on the indicating scale and can be very accurately centered, whereas comvparingthe wave peak position with a scale leads to great error, especially true where the curves are relatively fiat due to slight unbalances in the shaft.

It may be mentioned that the required length of the octagon mirror 15 is only about 1 .inch

in this machine, because only the peak of the wave is required to be projected, whereas with the conventional system a mirror length equal to the full width of the screen is required.

From the foregoing it will be seen that the screen used in this machine is .not required to be ruled or calibrated but only need be provided with a pair of hair lines at right angles to each other. .Still further, because all of the readings are taken at the intersection of these two lines,

is provided thereon which is in it is not only unessential but it is not desirable to include the remaining portion of the screen which is required to show a full wave. For this reason this machine has incorporated therein only that portion of the scale outlined by the rectangle I02 in Figure 14. The only operation required of the operator is that he center the wave peak over the cross hairs and then read the graduations on the two dials. There are, of course, two dials IOI, one for each of the telescopes, and the graduations on one of these dials may be varied to compensate for the weight of the driving shaft on one end of the crankshaft.

In order to protect the screen 16, a. plate glass cover I03 is disposed thereover, which in order to reflect exterior light from the operator's eyes is set at an angle, as shown. A shroud I04 isprovided so that the operator may look down through this shroud onto the screen 16 and all exterior light will be excluded from the screen.

In order that each end of the machine may be alternately read, I have provided a pair of each side of the machine. From Figure 12 it will be seen that upon the outer end of each of the telescopes I have provided an electrically operated shutter I08 which consists essentially of a solenoid having a plunger I II therein to which a light shutter H2 is secured. Normally, the plunger I I I is resiliently urged to position wherein its shutter obstructs the passage of light from the adjacent telescope. However, when the solenoid I08 is energized then the shutter is drawn up out of the light path and allows the light to pass from the telescope to the prism 1 I.

Due to the sensitivity of the indicating system, means are provided whereby the target may be adjusted to read exactly on the zero line when the device is at rest. This means also compensates for the effect of varying temperatures upon the machine. A pair of bimetal spring strips II8 are interposed between the plates 58 and the frame I5, these strips being secured by screws H9. A pair of adjusting screws I20 are provided so that the tension of these spring strips may be altered. These springs adjust the posivtion of the targets and further are designed to counteract the shifting of the target due to temperature changes. In this machine the target 60 must remain stationary when a true balance is reached and the target image must register zero amplitude on the screen 16. Either a positive or a negative reading of the image will cause an error in the balance reading. The adjusting screw I20 tensions the spring IIB to urge the target to a zero position. The spring H8 is formed of bimetal; however, if the machine could be operated continuously at a constant temperature sucha bimetal spring would not be required, because the base of the machine would then be at the same temperature as all of the'working parts. However, during the normal operation of the machine the device is idle during the night at which time the base of the machine, together with all of the parts therein, are reduced to atmospheric temperature. When the machine is started the light bulb 61, together with the solenoids 41 and coils 64, radiates heat which increases the temperature within the machine. This causes the members 53 and SI to expand more rapidly than the heavy base I5 and consequently the target 60 is forced to gradually shift from its central position. Correction is made by adjusting the screws I20 which change the tension of the springs I I8. Of course, a

switches I01 located in the cover 19, one on.

. bimetal strip I I8, but in such case the screws I20 would need be adjusted every minute or two until a constant temperature were reached by all the parts of the device. Such a condition results only after the machine has been in operation for several hours. Consequently, the function of the strips H8 is to compensate to a large extent for the frequent adjustment of the screws I20 which would otherwise be required to keep the targets at their central positions. The springs deflect upon an increase in temperature to practically duplicate a continuous adjustment by the screws I20.

The operation of the switch I01 located on one side of the machine energizes the solenoid Won the same side and at the same time energizes the locking solenoid 41 on the opposite side of the machine, thereby'pivotally holding the far end of the crankshaft and allowing the adjacent end to vibrate, the opposite solenoid I08 obstructing the light from the stationary target. When it is desired to read the unbalance on the other end of the machine, the other switch IOlI is operated which automatically reverses the connections thereby obstructing the light from the former and reversing the holding devices.

' The operation of the device is as follows:

The machine is first adjusted for the particular crankshaft or body to be balanced and the several lights turned on. The body is then laid in the supports I9 and the driving head pushed over the end and rotated until the driving key snaps into the keyway in the shaft. One of the knobs 33 is turned to startthe motor 20. The operator of the machine then presses one of the button switches I 01 thereby allowing the target image on the adjacent side to be projected upon the screen Hi. The center dial 90 together with the dial IN on the adjacent side of the'machine is then rotated until the peak of the wave is exactly centered on the cross hairs on the screen 16.. The operator then reads the angularity from the center dial and the amplitude or amount of unbalance directly from the otherdial. These two figures are marked on any convenient pad or even with chalk on the top of the cover I9 and without stopping the shaft the other button switch I! is depressed which reverses the operations ofthe clamping solenoid and light shutter switches so that the vibration of the other target is impressed upon the screen. Then the center dial and the other side dial is rotated until the peak of the wave projected is centered upon the cross hairs and then the crankshaft is stopped by means of the switch 33. The operator is provided with a gauge which he lays on the top of the machine so that he may turn the crankshaft to a predetermined angle as shown by the degree graduations on the driving head and then scribes this angle across one of the flanges l3. The angle for the opposite flange is also scribed in a like manner and then the inch ounces of unbalance is marked with chalk upon the sides of the flange. The crankshaft is then set up in a drill press which is provided with a feeding mechanism having an adjustable stopping device thereon, the adjustable device being calibrated to read in inch ounces so that the operator simply sets the adjustment at the markings on the face of the particular flange being drilled then rotates the crankshaft so that the scribed line is aligned with the drill and starts the machine. The machine then drills out sufficient metal to automatically balance the particular end of the shaft. The other end of the shaft is balanced in a like manner. The crankshaft is thus completely balanced so that it is not necessary to send the shaft back to the machine to check the accuracy of the work.

Referring to Figure 17, I have shown a preferred arrangement of machines which is particstationed beneath each conveyor line, whose duty it is to install and remove the crankshafts from the two adjacent machines. Another man is'located adjacent to the other conveyor line for the same purpose. Two operators shown by circles I I are stationed in between the two pairs of machines, these operators being required to alternately. read and mark the crankshafts on each of the adjacent machines. Experience has shown that it takes just about as long tounload a machine, place the crankshaft on the conveyor, then take an unbalanced shaft from the conveyor and install it in the machine as it does to read the machine and mark the readings on the shaft. Consequently, none of the machines are idle any portion of the time and still the maximum production can be obtained from the four machines with only four men.

Among the many advantages arising from the use of my improved device it may be well to repeat that the instrument produces a theoretically correct reading which should be distinguished from numerous other balancing-machines, the readings of which are only approximations.

Still further, for the reason thatthe indicator readings are shifted by micrometer adjustment to a zero point, the accuracy obtained with the machine is many times greater than what could be attained if an attempt were made to read the am plitude and position of the full wave on the scale, as was heretofore the custom with this type of wave indicating system.

Still further, the means whereby the whole supporting system is tuned to a frequency having its natural period of vibration slightly above the rotating frequency insures maximum amplitude of movement of the device resulting from very minute unbalances in the shaft. This sensitiveness is even further brought out because of the relatively light reciprocating parts employed in this machine in comparison to the heavy tables, cradles and the like employed in most other types of balancing machines.

Still further, the applicant provides a novel type of electric dampener, the effect of which can be exactly compensated for in the calibration of the machine.

Some changes may be made in the arrangement, construction and combination of the various parts of my improved device without departing from the spirit of my invention and it is my intention'to cover by my claims such changes as may reasonably beincluded within the scope cation of said indicating means to move from a zero position by the amplitude of said movement, and micrometer means whereby said indication when'deflected may be adjusted back to said zero position independently of said deflecting means, whereby the amount of deflection may be accurately ascertained .by the adjustment of said micrometer.

2. A dynamic balancing machine comprising, means for rotatably supporting the work to be balanced upon a'resilient support whereby unbalance in said work when rotated will cause said I support to oscillate, the amplitude of oscillation deflected may be adjusted to said zero position,

whereby the amount of deflection may be accurately ascertained by the adjustment of said micrometer.

3. A dynamic balancing machine comprising, means for rotating the work to be balanced and supporting same in such manner that unbalance therein causes reciprocating movement of the work support, an indicating means timed with said rotating means and actuated by said support to indicate the angle of unbalance by displacement of the indication of said indicating means from a zero position, and micrometer means whereby said indication when displaced may be adjusted back to said zero position independently of said timing, whereby the amount of displacement may be accurately ascertained by the position of adjustment of said micrometer.

4. A device, as claimed in claim 3, wherein said indicating means is actuated so as to cause the indication thereof to be projected upon a screen as the peak of a sine wave.

5. A dynamic balancing machine comprising, means for rotating the work to be balanced and supporting same in such manner that the unbalance therein causes reciprocation of the work support, an indicator, means for causing the indication of said indicator to move both by the reciprocation of the support and by the angular position of the work relative to said reciprocation, the amount of movement of said indication in one direction from a zero position indicating the amplitude of said reciprocation and the amount of movement of said indication in another direction from said zero position indicating said angular position, and independently operable micrometer adjusting means for shifting said indication in each of said two directions back to said zero position, whereby the amplitude of reciprocation and angular displacement of the unbalance may be accurately ascertained by the calibration of said adjusting means, respectively. 7

6. A dynamic balancing machine comprising, means for rotating the work to be balanced and supporting same for movement transverse to its axis of rotation caused by unbalance therein, an indicator, deflecting means actuated by the amplitude of said transverse movement causing the indication of said indicator to move in one direction from a zero line, deflecting means actuated by the angular displacement of said unbalance causing the indication of said indicator to move in a second direction from a zero line, said zero lines intersecting each other, and a pair of micrometer means for shifting said indication back in each of said directions to the intersection of said zero line positions, whereby the amount of deflection may be ascertained by the calibration of one of said micrometer means and the angularlty of said unbalance ascertained by the calibration of the other of said micrometer means.

7..A dynamic balancing machine comprising, a support adapted to rotatably mount the work to be balanced, said support being constructed so that dynamic unbalance in the work causes a proportional movement of the support, a. screen, means for projecting a light beam, means for moving said light beam across said screen in timed angular relation with said work, an angular scale on said screen, means for deflecting said beam laterally by and in proportion to the amplitude of movement of the work support to thereby project a sine wave upon said screen, means for measuring the amplitude and position of said wave and a dampening device connected to said support and restricting its movement comprising a plate disposed in a magnetic field so as to cut the lines of force in proportion to the movement of said support, the resistance offered to the movement of said plate being directly proportional to its speed, whereby the angular lag produced thereby can be exactly compensated for over the full range of the machine byaltering the graduations on the angular scale of the machine.

8. A device, as claimed in claim 7, wherein mechanically amplifying mechanism connects the work support and the dampener plate, whereby the speed at which the plate cuts the lines of force is proportionally increased.

9. A dynamic balancing machine especially adapted for balancing crank shafts comprising, a pair of laterally spaced supports adapted to rotatably mount a pair of spaced main bearings of said crank shaft in a horizontal position, said supports each being pivotally mounted in members capable of transverse reciprocation relative .to said crank shaft, means for rotating the work in said supports, and a pair of solenoid operated clamping jaws secured to said machine adjacent to each of said members, which jaws may be operatively clamped to said members so as to selectively secure said members in fixed position relative to said machine.

10. A device, as claimed in claim 7 wherein the means which connect said plate to said support transmits positive movement therebetween in both directions to thus dampen both ends of the oscillating stroke.

11. In a balancing machine, a support for rotatably mounting the work to be balanced, said support being mounted for oscillation due to unbalance in the work, a spring means adapted to control the natural frequency of oscillation of said support, indicating means oscillated by said support through connecting mechanism, and a temperature responsive means adapted to maintain said indicator in a fixed neutral position by compensating for the effect of temperature changes upon said connecting mechanism.

12. A device, as claimed in claim 11, wherein said temperature responsive means comprises a spring which resiliently urges said support away from its neutral position due to said controlling spring, the effect of said temperature responsive spring varying as the temperature of the machine varies.

13. A device, as claimed in claim 11, wherein said temperature responsive means comprises a bi-metal spring which resiliently urges said support in proportion to the temperature away from its neutral position due to said controlling spring.

EDWARD S. HUFF.