US2520514A - Automatic self-indexing commutator slotter - Google Patents

Description

Aug. 29, 1950 PE R 2,520,514

AUTOMATIC SELF-INDEXING COMMUTATOR SLOTTER Filed Oct. 16, 1947 4 Sheets-Sheet l INVENTOR, [Fu i/2 9 SpQCZ 'OI? 8 1950 1. SPECTOR 2,520,514

AUTOMATIC SELF-INDEXING COMMUTATOR SLOTTER Filed Oct. 16, 1947 4 Sheets-Sheet 2 INVENTOR, #0137 5,090 {'07: BY

Aug 29, 1950 1. SPECTOR 2,520,514

AUTOMATIC SELF-INDEXING COMMUTATOR SLOTTER Filed Oct. 16, 1947 4 Sheets-Sheet 3 INVENTOR., //Qb /79 flpecforr 17.7 f OK/Vf KS.

Patented Aug. 29, 1950 AUTOMATIC SELF-INDEXING COMMUTATOR SLOTTER Irving Specter, Miami, Fla.

Application October 16, 1947, Serial No. 780,248

9 Claims. 1

This invention relates to an automatic selfindexing commutator slotter.

An object of the invention is toeliminate the necessity of manually operating a cutting head or adjusting and aligning the mica segments to the cutter wheel, or removing the armature and placing it in a separate machine for the purpose ofslotting.

Another object of the invention is the incorporation of means whereby the mechanism may be folded back and locked out of the way so that i the lathe may be used unobstructed for other turnings.

A still further object of the invention is the production of an efllcient mechanism comprising mechanical and electrical means, depending on whether the armature has been turned perfectly smooth, with the mica flush, or if the grooves are still present and only need cleaning up, adjustments being provided for either condition; the mechanism alsoshuts off automatically at the completion ofthe slotting, when used with the electrical indexing method.

With the foregoing and other objects in view, my invention comprises certain novel constructions, combinations, and arrangements of parts as will be hereinafter fully described, illustrated in the accompanying drawings, and more'particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a view in front elevation of a mechanism constructed in accordance with the present invention, including an armature mounted in a lathe as in turning, and the slotting attach ment bolted to the rear of the lathe carriage and permanently aligned laterally withthe lathe centers, while Fig. 2 is a similar view with some of the elements shown in section, and some elements shown moved tothe right from the position shown in Fig. 1.

Fig. 3 is a side view, in elevation, showing some of the elements in vertical section.

Fig. 4 is an enlarged fragmentary view in elevation, of the mechanism shown in Fig. 3.

Referring to the drawings, in which the preferred embodiment of the invention is illustrated, I designates a motor of /12' /20 H. P., and 2 is a cam driven by said motor through a double reduction worm drive 3 mounted in a housing 3.

2 tached eye fittings 9 and ID, enabling the assembly to slide upon the shafts II and I2.

A reciprocating movement is obtained by the thrust of the cam wheel 2 against the stationary roller-member l3. The cam shaft l4 and the cam 2 are not attached to each other, but are of floating construction, the coupling being through a, pin l5 and driving-arm Hi. This arrangement permits the positive drive to be applied to the sliding carriage assembly to the left, which is the cutting stroke, and a comparatively speedier return action to the right motivated by the loading spring H. A dash-pot'l8 is attached to the fitting 9 as shown. The function of the loose-coupled cam 2 will be hereinafter more fully explained. a

The second major sub-assembly of the mechanism consists of the following: A brush l9 makes electrical contact with the projecting rim of the commutator 20, and is slideably attached to brush-holder 2|, by means of the retaining screws 22 in the slotted portion 23 of the brush [9 and held in contact with the spring 24, and a mounting-bar 25 which is affixed at its upper end to shaft H. A second brush 26 makes contact with the commutator body 21 (see Fig. 3),

An extension of this housing 4 carries the cutand has a slotted holder 28 slidably fixed to its mounting-bar 29 (see Fig. 3), by means of screws 30 and 3| in their respective slots 32 and 33, so that the cam 34will lift said holder 28 as the sliding carriage assembly passes under the roller 35 carried by said holder. The mounting-bar 29 and holder :28 are slotted at their lower ends to permit a sliding-plate 36 to project through them, and allow the vertically acting holder 28 to be raised and lowered by the said cam 34. The mounting-bar 29 isadjustable with respect to the commutators length by means of the threaded shaft 3'! having a grip 38 at one end and held in the bar 29 by the set collar 39. The bar 29 is guided by the rods 4|] and ll which pass through the member 2|. (See Figs. 1 and 2.) A shaft 42 is attached to the upper portion of the bar 29 and the end of said shaft 32! carries a stopping block 43 and switch-points 441 and 45.

A mounting consisting of two plates to of an electrical insulating material, the positions of which are indicated in only partial outline 0n the enlarged detail Fig. 4, in order to reveal the underlying parts, is pivoted to the member 29 by means of a shaft 41. An integral lug 58, forming one of a pair of anchorages for the compression spring 49, is affixed to the upper portion of the said mounting 46, and the other anchorage is formed by an extension of the guiding screw 34. It will now be clearly evident that the disposition of the mounting plates 46, the pivot 8'5, and the compression spring 59, is such as to permit a downward thrust to be exerted on the roller members 58, placing it into forceable contact with the commutator 2?.

The following cooperating mechanical parts and functions constitute a driving mechanism whereby an intermittent, controlled rotary motion is im-' parted t the commutator 2?. In the enlarged dc; tail, 4, showing this mechanism, a solenoid is supported in housing and contains a-suitable armature the lower end of which has aroller 54 thereon, normally engaging the pivotedplate 55, the said plate being normally held in'its up= ward extending position by virtue of the tension spring 55, the upper end of which is attached to the housing 51 and the lower=end to the push-rod 5S. The-said spring 56 has just sii flieienttensien to counterbalance the weight of the push rod 58, the plate 5 5 and the-solenoid armature 53 so that a maximum pressureis obtamed between the threaded members 59 and 6 when a suitable current is supplied to the said solenoid 52. The supply ancl'cont'rol of this current by suitable switches and contacts will be described more fully hereinafter; the mechanical actions resulting when the current is applied to the solenoid 5i being as follows: The armature 53 having been energized, depresses the plate 55 which in turn engages the push-rod 5S placing the threaded members 559 and S into engagement.

The sliding plate 36 which. carries with the push-rod housing 53' travels to the left guided by the member t? (see-Fig. 3), and a similar member 6%, which engage the slotted portion Si or the saidsliding plate at. This lateral movement, which is indicated in Fig. S'by the dotted alternate position A, is transmitted to the slotted lever 62 by means of a wrist-pints the said lever 52 being pivoted near its lower end tothe housing plates til. A ratchet arm 54' having integral ratchet teeth in its lower edge corresponding to a similarly toothed rotary member 65 ailix'ed centrally between the two outer frictional roller sections Elli, is pivotally attached to the lever 62. The outer end of the ratchet arm is provided with a grip Giiby means of which it may be raised and lowered, either position being maintained by the action of a, togg-le mounted tension spring 6?. A connecting link 63 is attached pivotally to the right extremity of the ratchet arm 54 and its opposite end'to the pivoted ratchet pawl $59. It will now be apparent that the commutator 2'! may be rotated anticlockwise (Fig 3) by either of'two means, first, by the lateral movement of the sliding arm 36 to the left as applied to the ratchet arm (i i, in the down position, and the turning force being applied to the commutator '2'! by the friction rollers 59, or secondly, by thesame lateral move ment of sliding arm 36 as applied to the ratchet pawl 59, the said pawl engaging slots It present in the surface of the commutator, when the a com aratively shallow turning procedure in which only suficient metal is removed from the any of the parts.

iccmmutators surface to true up minor wear, the slots still being in evidence as by the previous slotting operation but requiring going over. In the first instance above referred to, in which the commutator has been turned smooth and flush with its mica insulating sections, my invention provides electrical means of controlling the in- 'dexing operation, as follows.- In referring to the wiring elements in Fig. 4, it will be noted that a ,clearly defined electrical circuit exists through the following elements which are wired in series to the source of current L, L, namely, main switch H and i2, solenoid 5|, contact points 44 and 45, tangential contact brush 25, and peripheral contact brush IS, the said circuit being in continuity when a metal commutator segment as at 73 becomes tangential to both the brush 26 and any portion of the peripheral brush l9. It is now clearly evident that the mechanical rota-tion elements previously referred to, namely, 36, 62, c3, 64, 61, 558, and 69 are dependent upon the completion of the'electricalicircuit included by'the elements 5!, I9, '26, ll, 12, 44, i5, and a commutator bar 73, and can rotate the commutator 2i only a distance B before encountering thefollowing mica section and thus bringing the said rotation to an abrupt stop. The precise point it; at which this occurs is in exact axial alignment with'the path followed by the cutting stroke of slotting-Wheel 7, ofwhich more complete details are appended in the section headed Operating Cycle.

In: re-slotting =a commutator which has residual slots left in it by a shallow lathe turning procedure, the electrical circuit abovedescribed is ineffectual as an indexing means because the insulating medium afforded by the mica segments is absent. It is therefore one of my objectsto furnish asimpleand convenient means of changing from electrical to mechanical indexing in accordance with the oonditionofthe commutator slots, the method in use being determined by the operatoriby the'positionof'the lever es which, in its downward position, engages the friction roller members :58 to rotate a smoothly turned commutator with'the mica flush, the said mica providing the electrical indexing means, or, as in the case of a commutator. having residual slots, by raising the said lever (id to its'upward. posi tioncausing the pawl 69 to engage and rotate the commutator by means of the slots already by the stated means is-accomplishedwhen the pawl fiii has advanced the said slot to position it and any further movement beyond. this precise poi-ntis prevented'by the said pawl coming into physical contact with the tangential brush 26 at its recessedportion indicated by the dotted line at 15, the vertical face of which coincides with tangentpoint 14 of the-said brush and also the slotting wheels path of travel, Since the current supply to the solenoid is incapable of interruption at this phase in the operational cycle of the 'slotter, because of the absence of the micain'sula'ting segments at the commutators surface the rotation elementstiiffir'i, E2, 64, 63, ligand .69 continue to exertpressure against the pawl and :the 'saidipressure increasing until it overcomes the resistance of the compression spring d-Qwhereumn the housing -45 is forced to the left. Thus the over-travel of the rotation elements are absorbed safely without damageto The inter-related mechanical and electrical parts and functions by which the disengagement of the pawl is eifected prior to .a slotting cycle is as follows--in Figs. 1 and 2, it is the function, as has been previously explained, of cam 2 to provide primarily, areciprocating means for the transversely sliding slotting mechanism 8, 9 and I and secondarily by virtue ofthe loosely coupled cam drive [5, l6 and the tension spring I? to provide a pause interval at the com pletion of the return stroke in which to allow ample time for the transfer of power from the threaded arbor 6 to the rotation elements 62,53, 64 and 65. and for the completion of each indexing operation prior to each slotting operation. It has also been provided integrally in the slotter that. the pause interval be so timed by the speed of the motor I, the gear ratio of the Worm drive 3, the tension of the return spring ii, the adjustment of the dash-pot i8, and certain frictional considerations, that the expirationof this pause interval occurs coincidentally with the point of maximum over-travel of the lever 62 indicated by the dotted outline C. Fig. 1 shows the relation between contact points 44 and 45 and the position ofthe sliding carriage elements 8,

s, and I 5], which in Fig. 1 are at the extreme right and in Fig. 2 at the extreme left. This arrangement provides the required release of the driving mechanism actuating the pawl 69 at a point just preceding the actual slotting operation, by the movement of the sliding block fitting 9 to the left which releases contacts 44% and E5 and interrupts the solenoid circuit (Fig, i) permitting the housing 46 to resume its normal position relative to the commutator and the sliding arm 36 to its normal position.

Referring to Fig. 4 the means by which the main switch H and T2 is made to shut ofi auto: matically with the arm 64 set in its downward position, as in electrically indexing a smoothly turned commutator having flush mica, comprising the edge of arm 64 striking the edge of the movable contact arm 1 I, when said arm 64 moves upwardly, and deflect it towards the left as shown by dotted position D thus breaking the main current supply circuit when an over-travel of the sliding plate 36 carries the slotted arm to the extreme position C shown. It has already been shown that in the absence of mica at the surface of the commutator that over-travel of the rota tion members 36, 62, E3, and 64 must occur. In mechanical indexing this over-travel occurs on every indexing cycle but is prevented from opening the main switch points H and 12 by the 010+ sure of the shunt switch points 12 and 17 by the arm 64 in its raised position as shown in the 90 degree projected rotation of a section of these parts, Fig. 4. However, the shunt switch 16 and 11 is disengaged at the lower position of the arm 64 and the over-travel occasioned by the failure of the tangential brush 26 to function as a circuit breaker in the absence of the mica, as previously stated, causes the said brush 26 to bridge over the first slot that was out, after the said slot has made a complete clockwise rotation and thereby holding the solenoid circuit closed until the mechanical elements it has set into motion propel the slotted arm 62 into the extreme position C and deflecting the movable contact arm H of the said main switch, thereby stopping the entire operation of the slotter.

it is a further object of the invention to pro vide means for attachment of the above described mechanisms to any of the lathes commonly used for the turning operation on commutators prior to slotting. It is a prerequisite that the cutting l1 path .of the slotter be in. alignment with avertical projection of the lathesworking center line, the particular method by which this adjustment is made not being apart of this invention; but the preferred embodiment, which is merely a matter of manufacturing expediency, is as follows. The bracket 18 is constructed of such shape and thickness as to bring about the desired alignment between the vertical surface of the back of the lathes carriage and the lathes working centers, in accordance with the varying dimensions of the particular lathe to which the slotter is to be fitted. The method by which this bracket is is attached is shown in Figs. 2 and 3;. the slots [9 accommodate the bolts and secure the said bracket to the end of the lathe carriage by means of holes which are present in most lathe carriages for securing taper attachments to them. In reference to the varying heights between difierent lathe working centers and their respective carriages, this is compensatedfor by a vertical adjustment by which the primary mounting members consisting of shafts ll and l2 of the slotter mechanism are raised and lowered, not only for the above stated purpose, but also to provide a positive and gradual control for the depth of cut by the slotter.

It is also an object of the invention to provide means whereby the slotting device maybe folded back so as to permit the lathe to be used unobstructed for other turning operations. A preferred method of accomplishing this is clearly shown in Figs. 2 and 3 wherein a bracket 3| or yoke, shaped as shown in Figs. 1 and .2, surmounts the stationary bracket .78 and is pivoted thereto by a shaft 82, in Fig. 3. An extended portion of bracket it provides an anchorage for a pair of grips 83 which terminate in the threaded shafts 84, these engaging similarly threaded holes in the said bracket. The pivoted bracket at has slotted extensions 85 (see Fig. 3) in the form of quadrants which are radially concentric with the pivot shaft 82 the threaded shafts 84 previously noted engaging these slots, the adjacent sides of which provide friction surfaces for the tightening of the said grips 83 and thereby providing a holding medium for the slotter in either-its vertical operating position, or in its folded position as indicated by the dotted lines at E. i

A. preferred method for the vertical control of the slotter mechanism is shown in Figs. 1 and 2 in front e1evation.- The stationary shafts 86 are thetwo main vertical guide members. .These are secured at their lower ends to bracket BI and held ina parallel position by a cross member 81 at their upper ends, as shown in Figs. 1 and 2. The two horizontal guide shafts l l and [2 which comprise the main mounting members upon which the slotter mechanism slides are attached at their extremities to two Y-shaped brackets 88in the manner shown clearly in Fig. 3 and in the dotted extensions of the said shafts in the said bracket in Figs. 1 and 2. The members 83 and 90, which are attached to the yokes. as shown inFigs. 1 and 2 are slideably attached to the vertical. guide members Ed by suitable holes in them. The sliding member 89 is provided with a threaded hole at its center which is engaged by a similarly threaded shaft 9|, the upper portion of which is rotatably mounted by set collars B2 in themember 81, and has a rotation handle 83 affixed to its upper extremity by which the said shaft can be revolved and the cooperating vertically sliding members 88, 89 and 90, and the attached horizontal guide shafts I I: and t2 can be raised and-lowered.

Op ra i y le.

The'following describes. one completecycle of the operation of the slotting device. The slotter is attached to and aligned with the lathe for which it has been adapted as previously describedand the commutator of an'armature of the type previously indicated has been turned in the said lathe so that its radially disposed mica segments are flush with the commutators peripheral surface, the said armature then being left in the lathe as in turning. The driving means for the lathe headstock is then disengaged. Figs. 1 and 2 show the slotter longitudinally aligned by means of the-lathe s carriage control so that the left peripheral contact brush I 9 aligns with the outer edge of the commutators annular extended rim 20 and the right hand roller of member 50 aligned by means of the regulating member 33 so that its right hand edge coincides with that of the commutator. The slotter mechanism is then lowered by means of the vertical regulative screw and handle HI and 93 thereby placing the rollers into forceable contact with the commutators 27 periphery, the vertical adjustment being completed when the required depth of cut is obtained by visual alignment between the bottom of the slotter wheel! and the surface of the commutator. It is assumed that thesliding carriage assembly 8, 9, and I is at its extreme right position where it would normally rest after the completion of a previous slotting operation and that the driving pin l andarm 16 are not making contact which would also-be the case normally. The armature is thenpositioned radially so that the tangential brush 26 is making contact with one of the commutators metallic segments (Fig. 4). Next the ratchet arm 64 is placed in its down position (see Fig. 4) and the switch handle 56 to its on position, thereby starting the motor I and rotating the cutting spindle 6. Contact points 44 and 45 are closed at this point in the cycle as shown in Fig. 1, and a complete electrical circuit exists between the elements 5!, I9, 26, H, 12, 44 and 45 by which the solenoid, acting upon the mechanical elements 3%, 62, 63, 64, 68, 69, and is enabled to effect rotation of the armature. The rotation thereby effected is under considerable frictional restraint occasioned by the parts of the'lathe which necessarily rotate with the armature and of the parts in control of the armatures positioning" such as the tail stock center '94 or a chuck. These'combined frictional sources together with that ofthe peripheral brush l9 which is under spring-tensioned engagement with the rim 2c of the commutator 2! as previously explained act as a brake by which-the relatively smallamount of momentum acquired by'the rcvolving armature is instantly checked whenthe electric current which activates the said rotary movement is interrupted by the interposition of a mica segment. At the conclusion of this rotary movement and the subsequent abrupt cessation thereto the position of the mica is-correct for the slotting operation, it being in coincidence with the tangential point of the; brush 26and the'slotters cutting wheel 1- pa-th oftravel as shown in Fig.4, the said path of travel being in precise alignment with the saidtangential point of the brush26 and the mica segment. At this point the cam-driving arm l6, actuated by-the worm drive 3 has caught up with the drive pin t5 on the cam wheel 2 and started the sliding carriage 8 with the attached slotting mechanism to the left, opening contacts 44 and 45. The vertically slideable arm 28 with its attached tangential brush 26 is raised by the cam 34 at the proper instant to allow cutter shaft 6 and wheel 1 to pass under it. The sliding carriage 8 can travel to the left only as far as the diameter of the cam disk 2 permits a thrust in that direction, and the position of the member 25 is always stationary in respect to that limiting point; hence, this member serves as a guide for the left limit of the cutting stroke. The cutter mechanism having performed its function and slotted the mica now starts its return stroke in the groove it previously cut and the cam 34 raises the contact arm 23 and its attached brush 26 as previously noted. The carriage 8 is not power impelled on-this return stroke but is drawn to the right by the spring IT as the cam 2 passes dead center, this being possible by virtue of the loose coupling existing between the cam-shaft l4 and cam 2, said coupling consisting of the fixed pin l5 attached tov the face of the cam disk 2, which is-free to disengage the cam driving arm l6 at the position indicated in Fig. 2; an alternate subsequent position being shown in Fig. 1 wherein the carriage has completed its movement to the right.

Atthe completion of the final slotting operation and with the resumption of electrical contact between the tangential brush 26 and the metallic surface of the commutator, the rotation of the commutator proceeds as previously stated, but in the absence of the peripheral flush mica heretofore functioning as an interrupting medium, the tangential brush 2% merely by-passes and-bridges over the interstice from which the mica was removed by the initial slotting operation and thereby compels the said brush to electrically engage and contact two consecutive metallic commutator segments. 7 Thus a prolonged interval of activation is maintained in the solenoid, which persists until the cooperating mechanical elements have reached their extreme limit as shown in Fig. 4, in which the position 0 of the slotted lever 62 has contacted and deflected the moveable point and arm H of the main switch Hand 12 thus shutting off the main power supply to the entire slotter mechanism.

The operation of the slotter on a commutator having residual slots as by a previous slotting operation, in the case wherein a shallow lathe turning procedure has left such slots in evidence and which are required to be re-slotted to their proper depth and to be cleanly re-slotted because of burring tendencies of the copper bars over the slotted interstices, is essentiallythe same as described before, with the exception that-the ratchet arm 64 is raised to its up position at the-beginning of theactual slotting process, and the mechanism must be shut-off manually using the same lever 65 in its lowered position.

While, I-have described the preferred embodiment ofmy invention and illustrated the same in-the accompanying drawings, certain minor changes or alterations may appear to one skilled in the art to which this invention relates during the extensive manu fac ur of th s m a I. therefore, reserve the right to make such changes or alterations; as shall fairlyfa'll within the scope of the appended claims.

What I claim is:

1. In amachineof the class described, the

combination of a movable support, saidsupport provided with a pair of fittings, a carriage slidably mounted on said fittings, a motor on said support, a milling device depending from said carriage under said fittings, means connecting said motor and milling device for operating said milling device whensaid carriage moves in one direction, means for automatically returning said carriage to a set position, indexing means on said support, means electrically connecting said indexing means to said motor, a housing and means supporting said housing upon said carriage, said housing provided witha pushrod, said push rod being adapted to engage said milling device, a sliding plate fixedly secured. to said housing, a slotted plate provided at its lower end with a pawl, means connecting said motor and said milling device, and means electrically connecting said motor and said slotted plate, whereby. when the milling device has completed acycleof operation, said pawl will be operated to move a commutator.

2. A supporting frame including laterally spaced, vertical side members, a secondary frame slidably mounted "on said side members, said secondary frame including spaced side members and guide rods connecting the side members of the secondary frame, a bed slidably mounted on said guide rods, a motor mounted on said bed, a cam shaft driven from said motor, a cam rotatably mounted on said cam shaft, a fixed member carried by the secondary frame and having said cam engaging therewith, a cam operating arm fixed to said cam shaft, a pin projecting laterally from said cam for engagement by said arm during one are of rotation of the cam and disengaging from the arm during the remaining arc of rotation of said cam, a tension spring having one end fixed to said fixed member and holding said cam in contact therewith, a hanger depending from said bed, a bearing at the lower end of the hanger, an arbor journalled in said bearing and carrying an armature slitting mill, means driven by the motor for driving said arbor, and means to support a commutator rotatably in the path of said mill.

3. A supporting frame including laterally spaced, vertical side members, a secondary frame slidably mounted on said side members, said secondary frame including spaced side members and guide rods connecting the side members of the secondary frame, a bed slidably mounted on said guide rods, a motor mounted on said bed, a cam shaft driven from said motor, a cam rotatably mounted on said cam shaft, a fixed member carried by the secondary frame and having said cam engaging therewith, a cam operating arm fixed to said cam shaft, a pin projecting laterally from said cam for engagement by said arm during one are of rotation of the cam and disengaging from the arm during the remaining are of rotation of said cam, a tension spring having one end fixed to said fixed member and holding said cam in contact therewith, a hanger depending from said bed, a bearing at the lower end of the hanger, an arbor journalled in said bearing and carrying an armature slitting mill, means driven by the motor for driving said arbor, means to support a commutator rotatably in the path of said mill, and means operating by reciprocation of said bed and effecting step-by-step rotation of the commutator.

4. A supporting frame including laterally spaced, vertical side members, a secondary frame slidably mounted on said side members, said secondary frame including spaced side members i0 and guide rods connecting the side members of the secondary frame, a bed slidably mounted on said guide rods, a motor mounted on said bed, a cam shaft driven from said motor, a cam rotatably mounted on said cam shaft, a fixed member carried by the secondary frame and having said cam engaging therewith, a cam operating arm fixed to said cam shaft, a pin projecting laterally from said cam for engagement by said arm during one are of rotation of the cam and disengaging from the arm during the remaining are of rotation of said cam, a tension spring having one end fixed to said fixed member and holding said cam in contact therewith, a hanger depending from said bed, a hearing at the lower end of the hanger, an arbor journalled in said bearing and carrying an armature slitting mill, means driven by the motor for driving said arbor, means to support a commutator rotatably in the path of said mill, and means operating by reciprocation of saidbed and effecting step-by-step rotation of the commutator, said last means including an electric circuit controlled mechanism having a circuit closing contact movable into and out of engagement'with the commutator and camming means on the bed controlling the movement of the circuit-closer from the commutator.

5. A supporting frame including laterally spaced; vertical side members, a secondary frame slidably mounted on said side members, said secondary frame including spaced side members and guiderods connecting the side members of the secondary frame, a bed slidably mounted on said guide rods, a motor mounted on said bed, a cam shaft driven-from said motor, a cam rotatably mounted on said cam shaft, a fixed member carried by the secondary frame and having said, cam engagingtherewith, a cam operating arm fixed to said cam shaft, a pin projecting laterally from said cam for engagement by said arm during one are of rotation of the cam and disengaging from the arm during the remaining arc of rotation of said cam, a tension spring having one end fixed to said fixed member and holding said cam in contact therewith, a hanger depending from said bed, a bearing at the lower end of the hanger, an arbor journalled in said bearing and carrying an armature slitting mill, means driven by the motor for driving said arbor, means to support a commutator rotatably in the path of said mill, means operating by reciprocation of said bed and effecting step-by-step rotation of the commutator, and means including an electrically operated mechanism for rotating the armature, other manually operable mechanism for rotating said armature, and means for effecting selective operation of said last two mechanisms.

6. A supporting frame including laterally spaced, vertical side members, a secondary frame slidably mounted on said side members, said secondary frame including spaced side members and guide rods connecting the side members of the secondary frame, a bed slidably mounted on said guide rods, a motor mounted on said bed, a quick return mechanism driven by said motor and reciprocating said bed between the side members of the secondary frame, a hanger depending from said bed, a bearing at the lower end of the hanger, an arbor journalled in said bearing and carrying an armature slitting mill, means driven by the motor for driving said arbor, and means to support a commutator rotatably in the path of said mill.

7. A supporting frame including laterally we -m4 a commutator rotatably'inthe' path of said mill,

and means operatingby reciprocation "of said bed and efiecting' step-by-step rotation of the commutator;

8. A supporting frame including laterally spaced, vertical'sidemembers, asecondary frame slidably mounted onsaid side members; said-secondary frame includingspaced side membersand guide rods connecting the sidemembers ofthe secondary frame, abedslidably mounted oIr said guide rode, a" motor mountedpnsaid b'edi a'quiek return mechanism driven by said motor and reciprocating said bed between the sidemembers of the secondaryframe; a'h'anger depending from said bed, a=bearingat the lowerendof'the hanger, an arbor journalled insaid bearing and carrying anarmatureslitting mill; means driven by the motor' for driving saidarbor, means to support a commutator rotatably-in the-path of'said mill, andmeans operating by reciprocationcf saidbed and effecting step-by-step'rotation of the commutator, said last meansincluding an" electric circuit closing contact movable intb and out of engagement with the commutator and ca-mming means onthe bed controlling the" movement of the" circuit closer from the commutator.

9. A supporting frame includinglaterally 12 spaced; vertical sidmembeis; a'secondary'frame slidably mcunted on said side members, said-secondary frameincludin'g*sp aced side members and guide ro'd's connecting the side members- 0fthe secondary frame; abed' slidably' mounted on said guiderods; a motor mounted' on saidbe'd, a quick return me'cli'anism driven by said motor" and reciprocating saidbed between tlie side members of the'seoondaryframe; a hanger 'depending' from .saidbedj a hearing at thelbwer'end' of the hanger,

an arbor j ournalled in said bearing and carrying an armature slitting'mill, meansdriyeniby'the motcrforvdriving said a'rber, means to support a commutatbr rotatably the patl'i" of-said" mill, means operating byreciprocation of said bed 5 and effecting stepby-step*- rotation' of the commutator; and means including an electricallyoperated mechanismior rotatingtliearmature, othermanuallyoperablemeclianismfor rotating said armature; and meansfor e fiecting' selective operation of saidlast two mechanisms.

' IRVING SPECTOR.

REFERE'N-GES CITED The following references are oi record' in the file of I this patent:

STATES PATENTS Number Name Date 985341? flattersley etal Feb. 28, 1911 110611973 Bilton May 20, 1913 116173807" Hlefgott Eel); 15, 1927 139113574 Kane May'30; 1933 231891771" Pool n n Nov; 21,1939 233522278 Manley- June z'l; 1944 2;3'53'4'15'7? Fabian Aug. 1',1944 2393Z 727 Aber Janr29, 1946 224333564 KeIIeret-aI. Dec:30, 1947 224369423 Dbwd etall Feb. 24,1948

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