US3513523A

US3513523A - Machine and method for forming laminations for magnetic cores

Info

Publication number: US3513523A
Application number: US632242A
Authority: US
Inventors: Armin F Mittermaier; Lowell M Mason
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1967-04-20
Filing date: 1967-04-20
Publication date: 1970-05-26
Anticipated expiration: 1987-05-26

Description

May 26, 1970 A. F. MITTERMAIER ETAL MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES Filed April 20, 1967 y 1970" A. F. MITTERMAIER ETAL 3,513,523

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES Filed April 20. 1967 3 Sheets-Sheet 2 m t m v r h a m w 9 Ann ell M Mason,

Lzvr'msy.

y 6, 1970 A. F. MITTERMAIER ETAL 3,513,523

MACHINE AND METHOD FOR FORMING LAMINA'IIONS FOR MAGNETIC CORES Filed April 20. 1967 3 Sheets-Sheet 3 @Ztarmsy 3,513,523 MACHINE AND METHOD FOR FORMING LAMI- NATIONS FOR MAGNETIC CORES Armin 'F. Mittermaier and Lowell M. Mason, Fort Wayne,

Ind., assignors to General Electric Company, a corporation of New York Filed Apr. 20, 1967, Ser. No. 632,242 Int. Cl. H01r 43/04 US. Cl. 29-203 10 Claims ABSTRACT OF THE DISCLOSURE A gripper carriage is driven by a variable drive train to advance an end portion of magnetic strip material from an upstanding loop of strip material until the gripper carriage engages a first index stop with a springbiased engagement. With the gripper carriage biased against the stop, a first preselected length of the strip material is indexed for forming the first leg of a lamination. The indexed end portion of the strip material is bent at right angles by a forming shoe. A shoe release mechanism prevents the forming shoe from dragging the strip material and opening the bend. The gripper carriage then advances a second preselected length of strip material until a second index stop is engaged by the carriage with a spring-biased engagement thereby to feed out the strip material for the second leg of the lamination. The formed lamination is then severed and deposited on an indexing conveyor. These operations are repeated until a predetermined number of laminations are formed and deposited on the indexing conveyor. The laminations are then transferred by an ejecting bar to a stacking table.

In order to ensure a positive feed without shearing the index stops or a portion of the gripper carriage drive train as the positions of the stops are varied, the travel of the gripper carriage is correspondingly varied. A computing section of the machine computes the height of the core as laminations are formed and initiates recycling of the machine when the desired stack height has been attained.

BACKGROUND OF THE INVENTION This invention relates to machines and methods for forming laminations for magnetic cores. More particularly, it relates to improvements in machines and methods adapted for use in connection with magnetic cores comprised of laminations preformed of strip steel so that the flux path is essentially in the direction of rolling of the strip steel.

In the mass production of transformers using cores made from preformed laminations, it is desirable, if not necessary, to feed strip material through a machine at relatively high speeds in order to achieve the desired production rates. It will be appreciated that the strip material advancing mechanism of a machine producing preformed laminations must accelerate rapidly from a dwell position to a maximum speed and then decelerate to a second dwell position in the process of indexing the strip material. This starting and stoping will usually occur at least three times in the production of each individual lamination in a core.

In the past, when attempts have been made to feed strip material through a forming station at high speeds, one of the problems encountered has been the tendency of the forming shoe to drag on the bent material and open the bend.

Where the strip material is indexed by butting the end of the strip material against a stop, a problem has been encountered in accurately positioning the strip material at the forming and severing stations without dis- IStates Patent "ice torting the material. It is therefore desirable to provide a machine that will rapidly position the strip material but does not require that the strip material be butted against a fixed stop. It is also desirable that the machine be capable of handling the strip material at high rates of speed so that the overall production rate of the machine is maximized. In addition, it is desirable that the actual overall core dimensions and weight of steel in each core be held within design tolerances.

Accordingly, it is a general object of the present invention to provide an improved method and machine for forming a magnetic core for an electro-magnetic induction apparatus.

Another object of the invention is to provide an improved machine and method for making preformed laminations for a magnetic core wherein the production rate of the machine is maximized.

It is a more specific object of the present invention to provide a machine and method for making preformed laminations for a magnetic core wherein material is supplied without unduly straining the feeding mechanism.

SUMMARY OF THE INVENTION In accordance with one form of our invention, we have provided an improved machine for making laminations from strip material wherein a gripper carriage advances the strip material from a strip material supply means to a forming station. To provide the preselected lengths of strip material required to form the legs of the lamination, the gripper carriage is successively driven against a first and a second stop. The forming station includes a mandrel and a forming shoe, the forming shoe being supported for translational and angular movement relative to the mandrel. When the gripper carriage is against the first stop to feed out the first preselected length of strip material, the forming shoe is actuated with an angular movement to bend the first preselected length of strip material and the forming shoe is initially disengaged from the strip material with a translational movement thereby to prevent dragging the forming shoe against the material.

The improved machine also includes a means for indexing the stops to vary the preselected lengths of lamination formed for successive lamination layers. As the positions of the stops are varied to change the preselected lengths, the travel and speed of the gripper carriage is correspondingly varied. After the strip material is advanced by the gripper carriage against the second stop to provide the second preselected length of strip material, the bent end portion is then severed to form a lamination, the first preselected length forming one leg of the lamination and the second preselected length forming the other leg of the lamination.

In accordance with a more specific aspect of our invention, we have provided a strip supply arrangement utilizing an upstanding loop of strip material from which the gripper carriage draws its supply of strip material. The height of the loop is maintained within predetermined high and low limits by supplying strip material to the loop when the height of the loop falls below the lower limit. When the height of the loop reaches the upper limit, the supply of strip material from a strip material source, such as a reel, is stopped.

According to another aspect of our invention, the forming shoe is supported by eccentrically mounted bearings for translational and angular movement relative to the mandrel. The bending operation is carried out at the forming station by imparting a rotational movement to the forming shoe, and the forming shoeforces the strip material against the mandrel thereby bending the strip, material. To release the forming shoe, a translational 3 movement is imparted to the shoe by rotating the eccentrically mounted bearings. In this way, dragging of the material is prevented. After this initial translational movement, the forming shoe is rotated to its rest position.

For transferring laminations to a stacking station, we have provided a positioning conveyor that arranges the laminations in a prestacking position for transfer to the stacking station, the laminations being ejected from the prestacking position into stacked relationship on the stacking station. In this manner, a predetermined number of core sections, equal to the number of laminations in the prestacking position, are progressively built up.

In still another aspect of the invention, we have provided an improved method for making the lamination sections of a preformed magnetic core. In carrying out the method of the invention, laminations are formed at the forming station with a first and a second leg portion substantially at right angles to each other. A preselected number of substantially identical laminations are formed and positioned at individual stacking stations to form a first set of laminations. Subsequently, additional sets of substantially identical laminations are formed and stacked, one each, on the laminations previously positioned at each of the stacking stations. In the practice of our method, a free loop of strip material is maintained and the material is selectively advanced a first distance as determined by a first indexable stop; formed; released; advanced a second distance as determined by a second indexable stop; and severed in order to form each lamination. These steps are repeated to produce the requisite number of substantially identical laminations comprising each set.

The step of forming the strip material includes the step of positioning the material between a forming shoe and forming mandrel, and rotating the forming shoe on a shaft after moving the shaft toward the center of bend for the strip material. The bent strip material is then released by returning the shaft to its initial position and then rotating the shaft to return the forming shoe to its initial position.

After the last lamination for each set of laminations is completed, the indexable stops are moved incremental distances to determine the length of the legs of subsequent substantially identical laminations. The indexable stops serve as guides and present limits for the movement of a strip material gripper carriage.

In the practice of the invention, the strip material is grasped by the gripper carriage and it in turn is advanced a first distance to engage the first indexable stop with a spring-biased engagement. After the strip material has been formed, the gripper carriage is advanced a second distance to engage the second indexable element with a spring-biased engagement. Then the strip material is severed and the gripper carriage is returned to its initial position.

The subject matter which we regard as our invention is set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof may be better understood by the following description taken in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating a machine embodying our invention and groups of formed laminations being stacked in accordance with the improved method of the invention;

FIG. 2 is a mechanical schematic view, in perspective of the strip material thickness gauging station and indexing shaft for positioning indexable stops in the machine of FIG. 1;

FIG. 3 is an elevation showing the stacked relationship of laminations produced by the machine of FIG. 1;

FIG. 4 is an elevational view and shows the build of a core assembled from laminations produced by the machine illustrated in FIG. 1;

FIG. 5 is an elevation, with parts broken away, of a gripper carriage used in the machine of FIG. 1; and

FIG. 6 is an elevation, with parts in section, showing the forming shoe release mechanism used in the machine of FIG. 1; and

FIG. 7 is an exploded mechanical schematic of the drive mechanism for the machine of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, strip material 11 is pulled through a roller leveler 12 from a strip material supply 13 by pinch rollers 14 powered by motor 15. In order to reduce strain on the machine 10, we maintain a free loop 16 of material by using a suitable control apparatus for the motor 15. In the exemplification, the control apparatus is illustrated as including a control circuit 17, a pair of photo-cell scanning units 18, 19 and a pair of targets 21, 22.

During operation, the motor 15 is de-energized when the free loop 16 attains a height sufficient to interrupt the beam of light between the scanning unit 19 and target 22. As the material is fed out of the free loop 16 the loop drops down between guide bars 23 until the loop no longer interrupts the beam of light between photo-cell unit 18 and target 21. At this time, the windings of motor 15 are re-energized and additional strip material 11 is fed into the upstanding or free loop 16 until the upper light beam between photo-cell unit 19 and target 22 is again interrupted. In this manner, the upstanding loop is maintained for feeding strip material through the machine 10. It will be seen that the strip material 11 is fed through a material thickness gauging station 24, past a severing station 26, and to a forming station 27. As individual laminations 28 are formed and severed from the strip material they are pushed by a transfer arm 29 onto an indexing conveyor 31.

As the transfer arm 29 returns to an initial position, shown in FIG. 1, the indexing conveyor 31 advances one step to move a lamination 28 out of the path of the advancing strip material 11. When the desired number of substantially identical laminations 28 have been produced for a complete set of laminations, an ejecting bar 32 pushes each set of substantially identical laminations 28 against the backstop 33 on the pivotal stacking table 34. As the machine 10 continues to form laminations, they are then stacked on top of each other to form lamination groups 36.

When each of the groups 36 of laminations attain the desired height of individual laminations 28 to form core sections 35, the stacking table 34 is tilted to the dotted line position shown in FIG. 1 by an air cylinder 37 whereupon the core sections 35 slide onto an apron conveyor 40 for transfer to another location where core assembly operations may be performed.

Now having reference to FIG. 2, a more detailed description of the strip material thickness gauging station 24 will be made. The strip material thickness gauging station comes into operation in the exemplification after each set of four substantially identical laminations have been produced. The gauging station 24 is useful for making adjustments in the machine which cause each succeeding set of substantially identical laminations to differ in size from the preceding set of laminations by a predetermined amount, as will hereinafter be more fully explained.

With reference to FIG. 3, it will be seen that each of the laminations (A -A in group A have leg lengths differing from each adjacent lamination in the same group by essentially one stock thickness. The lamination B however, differs from the lamination A; by essentially 5 stock thicknesses. As explained in the US. Pat. No. 3,270,308 granted to Mittermaier this increased difference in leg length results in a stepped joint when the completed groups or core sections 35 are assembled to form a magnetic core such as core 38 in FIG. 4. It should be understood, however, that it is within the contemplation of the present invention that any number of laminations may be produced to form lamination group A and that the difference in the leg lengths of the first lamination in one group and the last lamination of a preceding subgroup may differ by any desired amount.

Again having reference to FIG. 2, the gauging station 24 includes actuating arms 39 and 41 useful for imparting selected increments of rotation through either disc 42 or 43 to the shaft 44. As best shown in FIG. 1, when shaft 44 and the lead screw or indexable cam 46 fixed thereto are rotated, indexable stops 47 and 48 move selected distances to determine the actual leg length of succeeding individual laminations. When motion is imparted to shaft 44 through disc 42, shaft 44 will be rotated an amount corresponding to one stock thickness of material, Whereas when motion is imparted to shaft 44 by disc 43 the shaft will be rotated an amount corresponding to five stock thicknesses of material.

When the strip material thickness gauging station 24 is not in use, or while substantially identical laminations are being produced, the clamp 49 is released from disc 42, and the stationary clamp 51 holds shaft 44 against rotation by clamping disc 42 keyed to the shaft 44.

While in this locked condition, the contact section 52 of the actuating arm 39 bears against the end of stock thicknesses measuring lever 53 to stretch tension spring 54 and raise gauging edge 56 of gauge block 57 from the strip material 11.

It will be understood that for purposes of illustration and description the gauging station 24 in FIGS. 1 and 2 has been shown as being adapted for manual operation. However, it will also be understood that the various functions described above can be fully automated by the use of cams, levers, and gears timed into the main drive train of the machine 10.

At selected times during dwells in the advance of strip material 11 through the machine 10, the clamp 49 is manually released by handle 58 whereupon the tension spring 54 causes edge 56 of gauge block -7 to pinch the strip material 11 against the machine bed 59. The corresponding movement of the end of the measuring lever 53 moves section 52 of actuating arm 39 upwardly an amount depending on the actual thickness of the material 11. After movement, the section 52 of actuating arm 39 is spaced from the stop 61 by an amount proportional to the thickness of the stock at the point of measurement plus any desired space factor.

When the shaft 44 is to be rotated one incremental amount corresponding to a single stock thickness, the clamp 49' is tightened so as to lock actuating arm 39 to disc 42, the stationary clamp 51 is released, and the handle 62 is moved manually to bring the section 52 of arm 39 into engagement with the stop 61.

It will be understood that the motion of handle 62 is imparted to shaft 44 through disc 42 and that rotation of shaft 44 results in an indexing of stops 47 and 48. After indexing, clamp 51 is retightened to hold the disc 42 and shaft 44; the clamp 49 is once more released, and the handle 62 is used to release the strip material 11 for advancement through the machine.

The shaft 44 may be indexed an amount corresponding to five stock thicknesses by proceeding as above, by imparting the indexing motion through the clamp 63 and disc '43 rather than the clamp 49 and disc 42. After clamp 49 has been released to permit actuation of gauging block 57 by the spring 54, clamp 63 is locked to disc 43 by turning handle 64. After release of clamp 51, contact section 52 is moved into engagement with the stop 61 as before. The movement of actuating arm 39 is multipled by a factor of 5 through gear train 65, 66, 67, 70 and transmitted to shaft 44 through clamp 63 and disc 43.

In FIG. 5 the gripper carriage 68 is shown in detail. Strip material 11 is gripped between an upper jaw 69 integral with the gripper carriage 68 and a movable lower jaw 71 which is normally urged into a closed position by the compression springs 72, 73. The

springs

72, 73 are seated on

pins

74, 76 projecting from

ledges

77, 78 integral with the body of the gripper carriage 68 and on pins 79, 81 projecting from bearing surfaces 82, '83 on the movable jaw 71. At selected times during the operation of the machine 10, the movable jaw 71 is opened against the bias of the

springs

72, 73 by the action of jaw release lever 84 which is pivotally mounted on the gripper carriage 68. The contact surface 89 of the jaw release lever 84 bears against the shelf 91 integral with the movable jaw 71 and opens the jaws when the roller 93 on the opposite end of the jaw release lever 84 is moved to the phantom line position (illustrated in FIG. 5) by the jaw release track 94.

The gripper carriage 68 is guided for movement through the machine by guide rods 96-, 97 on which the gripper carriage 68 is slidably mounted. Motion is imparted to the gripper carriage 68 by a dimensionally stable, i.e., essentially non-stretchable driving member illustrated as a flat steel band 98. The steel band passes through a bore 99 1n the gripper carriage 68 and is releasably connected to the gripper carriage 68 through a lost motion coupler generally denoted by the numeral 101.

Once the machine 10 has been set up, the

set screws

102, 103 are tightened against clamping

flats

104, 106 and the position of the lost motion coupler 101 relatrve to the steel band 98 is not changed except for occasional adjustments. When the abutment block 107 on the gripper carriage 68 engages the indexable stops 47, 48 the movement of the gripper carriage 68 along the

guide rods

96, 97 is stopped. However, since it is extremely difficult in a high speed production machine to keep absolute tolerances and the steel band is substantially non-stretchable, it would be possible to snap the steel band or shear the abutment block 107 if the lost motion coupler 101 were not used. With the lost motion coupler 101 the further advantage results that it is possible to overdrive the steel band 98 at all times to insure that the gripper carriage 68 is driven to exactly the correct position as determined by the indexable stops 47 and 48. In addition, minor misadjustments of the drive mechanism for steel band 98 may be tolerated because the lost motion coupler 101 will absorb any excess drive action.

The lost motion coupler 101 includes a pair of flanged collars 108 fixed to the gripper carriage at either end of the bore 99 through the carriage. Within the bore 99 a compression spring 109 is compressed between a pair of shouldered washers 110 which are held therein by the flanged collars 108. A clamping dog 111 is slidably received in a central opening through the flanged collars 108 and the

set screws

102, 103 hold the clamping dogs 111 in position on the steel band 98.

During operation of the machine 10 the gripper carriage 68 advances material to the left as viewed in FIGS. 1 and 5. As abutment 107 engages the indexable stops 47, 48, movement of the gripper carriage 68 ceases. However, with an intentional slight overdrive of the steel band 98 the left hand clamping dog 111 is moved to the left a small distance along the bore 109 and the right hand clamping dog 111 drives the right hand shouldered washer 110 along the bore 109 to compress the compression spring 99.

When the gripper carriage is returned to an initial position the clamping dogs 111 are driven to the right relative to the gripper carriage 68, and the spring 109 prevents damaging shock forces. With the exemplified lost motion connector 101, the gripper carriage abutment block 107 is essentially spring loaded against the indexable stops 47, 48 during dwell periods, and bears against the indexable stops 47, 48 with a substantially constant predetermined pressure of engagement.

Now having reference to FIGS. 6 and 7, we will more fully describe the operation of the pressure release mech anism 112 at the forming station 27. When strip material 11 has been advanced the first feed distance, it will move between the forming shoe 113 and the forming mandrel 114. A relatively wide range of thicknesses of strip material may move between the forming shoe 113 and forming mandrel 114 since the forming shoe 113 is spaced below the mandrel a distance greater than the thickness of the heaviest gauge of strip material contemplated to be bent at the forming station 27. The forming shoe 113 is keyed to a rotatable shaft 125 which is supported in a bearing surface 115 (see FIG. 6) in the eccentric 116 which forms part of the pressure release mechanism 112. The eccentric 116 in turn is supported in a fixed bearing 117 in the machine frame 118. In order to bend the strip material 11, the quadrant 119 is actuated through linkage 120 driven by cam 121 to drive pinion 122 keyed to the forming shoe shaft 125. However, just before the quadrant 119 is actuated, the linkage 123, driven by the cam 124, rocks the pressure arm 126 into engagement with the pressure release mechanism 112 and rocks the pressure release mechanism 112 against the compression spring 127 held in the machine frame 118. Thus, due to the movement of the pressure release mechanism 112 the forming shoe 113 is moved up against the strip material before the shoe rotates with shaft 125 to form the strip material 11. Just before the quadrant 119 returns to its initial position to return the forming shoe 113, the pressure arm 126 is released, the compression spring 127 returns the pressure release mechanism 112 to its initial position, and as the shaft 125 returns to its initial position, the forming shoe 113 moves obliquely away from the forming mandrel 114. With this arrangement, not only can a wide range of stock sizes be accommodated, but the tendency of the forming shoe 113 to drag the bent material and open the bend is substantially eliminated.

Turning to FIG. 7, we will now describe the overall operation of the machine in more detail. The strip material 11 is advanced through the machine 10 by the gripper carriage 68 through the action of capstan 128 which pays the steel band 98 off on one side and takes the steel band 98 up on the other side. As will be described more fully hereinafter, the capstan 128 not only advances the carriage 68 between dwells but also provides a fast return of the carriage 68 while the severing operation is being performed.

At the beginning of each feed cycle, the jaw release track 94 is moved downwardly, by the action of linkage 129 and the carriage cam 130, to permit the

jaws

69, 71 to close on the strip material 11. At about this same time, rake-off or transfer arm 29 is moved from the position shown in FIG. 7 to the position shown in FIG. 1. The rake-off arm 29 is rocked upwardly by the action of linkage 131 and lift cam 132. With the actuation of linkage 131, the rake-off rocker 133 stretches tension spring 134.

While the rake-off arm is rocking up, return cam 136 rocks linkage 137 to pull the rake-off slide 138 along the guides 139, 140.

The gripper carriage 68 accelerates, advances the strip material 11, and decelerates as abutment 107 on carriage 68 engages the first indexable stop 48 and excess drive action is absorbed by the lost motion coupler 101. As the stop 48 is engaged, capstan 128 dwells momentarily, and

linkages

120, 123, at the forming station 27 are actuated by the cams 121, 124, to bend the strip material 11.

The pressure release mechanism 112 and forming shoe 113 return to their initial positions, a release lever not shown, similar to jaw release lever 84 and carried by block 141 moves the indexable stop 48 downwardly against compression springs and out of the path of abutment 107 on gripper carriage 68. The release lever for the indexable stop is actuated by a release track connected through linkage 142 with cam 143 and essentially identical to jaw release track 94.

As the stop 48 drops out of engagement with the abutment-107, the capstan 128 operates to advance the gripper carriage 68 to the second indexable stop 47, whereupon the capstan 128 decelerates and dwells as the abutment 107 is pressured against the indexable stop 47. During this second dwell period, linkage 144, driven by face cam 146, moves clamp 147 to hold the strip material 11 against movement. The linkage 129 is then driven by cam to rock the release track 94 to an upward position to open the gripper jaws 69, 7-1, whereupon the capstan 128 returns the gripper carriage 68 to a start position and pressures the gripper carriage bar 148 against the machine stop 149. While the capstan 128 is returning the gripper carriage 68, the cam 150 actuates a shearing blade 151 through the linkage 152.

The shearing blade, pivotally mounted on the machine frame at 153, is aligned by guide 154 and the back surface of forming mandrel 114. As the bent lamination is severed, the rake-off arm 29 drops from the position shown in FIG. 1 to move the severed lamination onto the indexing conveyor as shown in FIG. 7. While the rake-off arm 29 is moving the last of a set of laminations onto the indexing conveyor 31, and before the gripper carriage 68 advances, the strip material thickness gauging apparatus illustrated in FIG. 2 is used to index shaft 44 and adjust the position of indexable stops 47, 48.

Since it is desirable to drive abutment 107 into the indexable stops 47, 48 with essentially the same pressure of engagement in each cycle of the machine, the drive train for capstan 128 is continually adjustable.

The drive for capstan 128 is derived from

cams

155, 156 which are designed to accelerate and decelerate the capstan 128 between dwells. Adjustment of the drive train between

cams

155, 156 and capstan 128 is accomplished by changing the position of drive pins 157, 158 in slots 159, 160 to change the effective crank length of

drive arms

161, 162. Vertical channels 163, 164 are guided on horizontal guide ways 165, 166 and are useful for changing the rocking motion of

drive arms

161, 162 to a straight line reciprocating motion. Trunnions 167, 168 carry the drive pins 157, 158 and are positioned in the channels 163, 164 by vertically adjustable cradles 169, 170.

As can be seen in FIG. 7, the

cams

155, 156 are keyed to the main drive shaft 171 of the machine 10. It will be understood, however, that due to the different configuration of the cam surfaces of these two earns, the movement of

drive arms

161, 162 are in phase with each other only during preselected times in each cycle. The cam drive action includes a first drive interval, a second drive interval, and a return interval. These three intervals correspond to the advance of the gripper carriage 68 to indexable stop 48, the advance of the gripper carriage to indexable stop 47, and the return of the gripper carriage 68 to an initial position against machine stop 149. During the first drive interval, the shaft 172 of capstan 128 undergoes pure rotation to feed the steel band 98 in the direction indicated by the arrow 1. The rotation of capstan 128 is affected 'by the linear movement of horizontal gear rack 173 in the direction of the arrow K. During the second interval of motion, the bearings (not shown) which support the capstan shaft 172 for rotation are translated horizontally in the direction of arrows L by the action of the pushrod -174 while the horizontal gear rack 173 is held stationary.

Since the rack 173 does not move while the shaft 172 and pinion 176 are being translated in the direction L, the pinion 126 rolls along the rack 173. Thus, the steel band 98 is paid off by the capstan 128 in the direction of the arrow I during the second drive interval due to the accumulative effect of translating and rotating pinion 176 and capstan 128. It will be understood that during the first drive interval, the drive action for horizontal rack 173 is derived only from the drive pin 157 and that during the second drive interval drive action is derived from drive pin 158.

In the exemplification, both drive

arms

161 and 162 dwell for a short period of time immediately following the second drive interval, whereupon both drive arms are returned to their initial positions. The return of both drive

arms

161, 162 results in a fast return of the capstan 128 to its original position.

As the positions of the indexable stops 47, 48 are changed during operation, the cradles 169', 170 are moved so that the drive action of capstan 128 is adjusted a corresponding amount. Thus, as the indexable stop 48 is moved by lead screw 177 in a direction to foreshorten the first and second feed distances of the gripper carriage 68, the horizontal rack 178 is moved a corresponding distance. Through the gearing 179-184 the horizontal movement of rack 178 is transformed to a vertical movement of the trunnion positioning cradles 169, 170. It will be understood that the camming surface 186 has a greater pitch than camming surface 187 on lead screw 177, and that the gear ratio of pinions 179 and 182 is selected accordingly.

As the cradles 169, 170 reduce the effective radius of

drive arms

161, 162, the first and second drive velocities will be reduced a proportional amount. In order to maintain the average feed rate of the strip material 11 through the machine at an optimum feed rate, provision is made to increase the operating speed of the main drive motor 188. Accordingly, the rheostat 1-89' of a conventional DC motor speed control 190 is mechanically driven from the pinion shaft 191 to increase the speed of motor 188 in proportion to the reduction of effective drive arm radius. With this arrangement, it will now be seen that we have provided an adjustable drive for the gripper carriage 68 which will reduce the stroke of the carriage but maintain the carriage velocity substantially uniform regardless of the size of laminations being made by the machine 10.

It is important that the machine 10 produce suflicient laminations prior to recycling that the final build or thickness of the core section 38 indicated by the dimension X in FIG. 4 approximate a nominal design value. Therefore, we have included a data storage mechanism that essentially continually sums the thicknesses of the laminations produced for each core 38. When the total thickness of laminations approximately equals the predetermined core build dimension X the machine recycles; apron conveyor 40 indexes a step while table 34 dumps core sections 36 onto the apron conveyor 40, and the laminations of the next succeeding core are produced.

The movement of the build bar 193, removably carried on stop block 141, performs the summing function. When the carriage 38 is resting against machine stop 149, the distance between build bar 193 and limit switch 192 is proportional to the total thickness of laminations needed to complete a core having a nominal dimension X. In the exemplification, this proportion is 2:1 due to the desired stepped joint core configuration which results from a five increment index of shaft 44 :after every fourth set of laminations. Therefore, the distance between the build bar 193 and limit switch 192 should be dimensioned by two stock thicknesses each time the build bar 193 indexes toward the limit switch 192. During operation, the build bar indexes toward the limit switch 192 one, one, one, and five stock thicknesses relative to the frame of machine 10. Thus, in order to reduce the distance between the build bar 193 and limit switch 192 two stock thicknesses during each index, the limit switch 192 must move both back and forth relative to the frame of the machine 10. With operation of the back-oif mechanism 195 in FIG. 7, the limit switch 192 backs away from the build bar 193 a distance approximately equal to one stock thickness each time the build bar 193 indexes one stock thickness, but moves toward the build bar 193 an equivalent of three stock thicknesses when the build bar 193 indexes five stock thicknesses.

With reference to FIG. 7, it will be seen that the backolf mechanism- 195, pivotally mounted at 196 and biased by tension spring 197, rides the stepped surfaces 198201 of surface cam 202. The surface cam in turn is driven from shaft 171 through the 6:1 Geneva movement 203 and gear 204 having a 3:8 ratio with respect to the cam 202. Thus, the cam 202 will index 16 times and complete one revolution, for every sixteen revolutions of the main drive shaft 171. The floating of limit swtich 192 back and forth insures that the distance between the build bar 193 and limit switch 192 is diminished by two stock thicknesses every index and that the actual core build will approximately equal a nominal value.

When the machine 10 recycles, the indexable stops 47, 48, and tnunnions 167, 168 are returned to their initial positions by rotating lead screw 177 in a reverse direction. One arrangement that has proved to be satisfactory in practice has included a control circuit 206 which is connected to limit switch 192. Closing of limit switch 192 then results in de-energization of the magnetic clutch 207, and energization of a return motor and magnetic clutch (not shown) connected to shaft 44 which results in a recycling of the lead screw 177.

Laminations for a number of diiferent sized cores 38 may be produced with the machine 10, without requiring the replacement of dies, gears, and other machine elements,

the replacement of which is usually required in conventional punch press type machines. When it is desired to produce a different size core with the presently disclosed machine 10, it is only necessary to establish the initial position of the gripper carriage 68 by the replacement of a gripper carriage bar 148 having an appropriate length and to change the length of the gauge bar comprising the second indexable stop 47. The build of the core will be determined by the selected length of build bar 193. The drive train for the gripper carriage can be adjusted by repositioning gripper carriage 68 relative to the steel band 98 and breaking the connections between pinions 180, 183 and vertical gear racks 181, 184 to adjust the position to trunnions 167, 168.

From the foregoing description, it will be apparent that the present invention makes it possible to readily fabricate laminations for preformed magnetic cores at a maximized feed rate wherein compensation is continually made for the thickness of the strip material used to make the laminations, and core build tolerances are very closely maintained. It will also be apparent that apparatus embodying the present invention can make many different sizes of laminations without requiring extensive tooling changes. Although in the illustrated exemplification of our invention, we have shown and described a core forming machine wherein a strip material thickness gauging station is adapted for manual operation, it will be appreciated that the basic operation performed at the strip material thickness gauging station is adaptable to completely automatic manufacturing techniques. Further, the particular embodiment of our invention, which we have disclosed, clearly illustrates the principles of operation of the invention, and as a result of this disclosure, many modifications will be apparent to those skilled in the art. Accordingly, it is to be understood that we intend by the appended claims to cover all such modifications that fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A machine for making laminations from strip material for preformed magnetic cores formed of core sections defining a plurality of lamination layers, said machine comprising: a strip material supply means, a forming station including a mandrel and a forming shoe, a gripper carriage for advancing the strip material to the forming station, drive means for driving the gripper carriage, at least a pair of stops for limiting the travel of said gripper carriage to selectively provide preselected lengths of strip material, said forming shoe supported for translational and angular movement relative to said mandrel whereby said forming shoe is actuated with an angular movement to bend at least one of said preselected lengths of strip material and said forming shoe is initially disengaged from the strip movement with a translational movement to prevent dragging of said strip material, means for indexing said stops to vary said preselected lengths of strip material for forming successive lamination layers, means responsive to the indexing of said stops for adjusting said drive means thereby to vary the travel and speed of said gripper carriage, means for severing said laminations after said strip material is advanced to provide one other of said preselected lengths, a stacking station and a transfer means for transferring laminations to said stacking station, said transfer means including a lamination positioning conveyor for moving a predetermined number of laminations into a prestacking position for transfer to the stacking station and an ejector for placing said predetermined number of laminations positioned in said prestacking position into stacked relationship at said stacking station to build up core sections, and means for recycling the machine when the laminations for at least one magnetic core of a predetermined stack height are formed.

2. A machine for making laminations from strip material for preformed magnetic cores, said machine comprising: a strip material supply means, a forming station, a strip advancing means for selectively feeding strip material to said forming station in preselected indexed lengths, said strip advancing means including a carriage for holding the strip material, at least a pair of index stops for limiting the travel of the carriage, a driver for imparting to said carriage a preselected mode of travel, and a drive train coupled with said driver, said driver including means for accelerating and decelerating said driver as the strip material is'being advanced to impart said preselected mode of travel for different positions of said index stops, shearing means for cutting off the lamination, a stacking station for assembling laminations for a predetermined number of core sections, and means for transferring laminations to said stacking station including a positioning conveyor for arranging the laminations into a prestacking position for transfer to said stacking station, and means for ejecting said laminations from said prestacking position on said positioning conveyor into stacked relationship at said stacking station thereby to progressively build up the stack height of said predetermined number of core sections.

3. The machine set forth in claim 1 wherein said predetermined number of laminations positioned on said positioning conveyor in said prestacking position is equal to the number of core sections to be stacked at said stacking station.

4. Apparatus for making laminations for a preformed magnetic core from strip material, said preformed magnetic core being formed of at least a pair of core sections, said apparatus comprising: a strip material supply means, a forming means including a forming shoe and a mandrel for bending an end portion of the strip material substantially at right angles, shearing means for cutting off the lamination, a strip length feeder, a driver coupled with said feeder for advancing said strip length feeder to selectively supply strip material in preselected indexed lengths to the forming means, a stacking station for assembling the laminations, and means for transferring the laminations to said stacking station, said last mentioned means including a positioning conveyor for moving a preselected number of laminations into a prestacking position for transfer to said stacking station, and means for moving the laminations from said prestacking position into a stacked relationship at said stacking station thereby to build up the core sections.

5. The apparatus set forth in claim 4 wherein said preselected number of laminations positioned in said prestacking position on said positioning conveyor is equal to ,the number of core sections to be built up at said stacking station.

6. The apparatus set forth in claim 4 wherein said stacking station includes an alignment bar for maintaining the alignment of the laminations being stacked at the stacking station to build up said core sections and said means for moving laminations from said prestacking position on said positioning conveyor includes an ejecting bar for simultaneously ejecting all of said predetermined number of laminations in said prestacking position toward said alignment bar to thereby arrange said laminations in stacked relationship with the other laminations at said stacking station.

7. The apparatus set forth in claim 4 wherein said strip material supply means includes an upstanding loop of strip material for feeding material to said strip length feeder, the height of said loop being maintained within predetermined high and low limits by supplying strip material to said loop when the height of said loop falls below the lower limit and by stop ing the supply of strip material to said loop when the height of said loop reaches the upper limit.

8. The apparatus set forth in claim 4 wherein said forming shoe is supported by eccentrically mounted bearings for translational and angular movement relative to said mandrel, said translational movement being imparted to said forming shoe by rotating said eccentric bearing support and said rotational movement being imparted by rotating said forming shoe.

9. The machine set forth in claim 2 wherein said predetermined number of core sections being built up at the stacking station is equal to the number of said laminations arranged in said prestacking position on said positioning conveyor.

10. A method of making L-sha'ped laminated core sections for a magnetic core, said method comprising the steps of: maintaining an upstanding loop of strip material, intermittently advancing the strip material from said upstanding loop to a forming station and to a severing station to produce a set of laminations having substantially the same size and shape, arranging said set of laminations in a prestacking position, and simultaneously ejecting said laminations from said prestacking position into stacked relation at a stacking station to build up a predetermined number of L-shaped laminated core sections, said predetermined number being equal to the number of laminations in said set arranged in said prestacking positions.

References Cited UNITED STATES PATENTS 2,956,381 10/1960 Chauvin et al. 2146 X 3,056,513 10/1962 Von Gal 214-6 3,096,805 7/1963 Biggs et al. 29609 X 3,220,568 11/1965 Voyce et al. 29-203 X CHARLIE T. MOON, Primary Examiner C. E. HALL, Assistant Examiner US. Cl. X.R.

Dedication 3,513,523.Armin F. Mittewnaier and Lowell M. Mason, F 011 Wayne, Ind. MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES. Patent dated May 26, 1970. Dedication filed Sept. 22, 1971, by the assignee, General Electric Company. Hereby dedicates to the Public the remaining term of said patent.

[Ofioial Gazette January 4, 1.972.]