US3189984A

US3189984A - Laminated core banding apparatus

Info

Publication number: US3189984A
Application number: US783987A
Authority: US
Inventors: William E Haifley; Edward J Schaefer; Lee J Lakes
Original assignee: Franklin Electric Co Inc
Current assignee: Franklin Electric Co Inc
Priority date: 1958-12-30
Filing date: 1958-12-30
Publication date: 1965-06-22
Anticipated expiration: 1982-06-22

Description

INVENTORS. ml? Qzf 4 Sheets-Sheet 1 113 17 J03 zz/l-zzm fia'zz/ardJScfi .[ee JZa/vea W. E. HAIFLEY ETAL LAMINATED CORE BANDING APPARATUS June 22, 1965 Filed Dec. 30, 1958 June 22, 1965 w. E. HAIFLEY ETAL LAMINATED CORE BANDING APPARATUS 4 Sheets-Sheet 2 Filed Dec. 50, 1958 INVENTORS.

Z Q1/6Z76i J 50% w w 1 Y 1 II lee flaw June 22, 1965 E. HAIFLEY ETAL LAMINATED CORE BANDING APPARATUS Filed Dec. 30, 1958 llllllv I l-l-l- II IIIIII/I///% 4 Sheets-Sheet 3 INVENTORS.

173 Iduard J6 e7;

1766 Jljazkee, @001, M /J4." dim June 1965 w. E. HAIFLEY ETAL LAMINATED CORE BANDING APPARATUS 4 Sheets-Sheet 4 Filed Dec. 30, 1958 INVENTORS EduardJScfiaefier lee Jlakes, a

i Q Q i imrln 1 .g n :4 P|L FllllhlL 5 i w m i? United States Patent r 3,189,934 LAMINATED CGRE BANDING APPARATUS William E. Hadley, Edward J. Echaefer, and Lee 1'. Lakes, Blutfton, IndL, assignors to Franklin Electric (30., Inc, Blufiton, Ind, a corporation of Indiana Filed Dec. 30, 1953, Ser. No. 783,987 7 Claims. (Cl. 292tl5) This invention relates to the manufacture of cores for electric machines and more particularly a method of, and apparatus for, assembling such cores.

The cores used in most present day electric machines are laminated structures having the laminations held together in stacked relation by rivets, welds, keys, and the like. It has been found that cores held together by keys or banding strips mounted in grooves extending longitudinally of the core have better magnetic characteristics than riveted or Welded cores. However, the various prior modes of assembly using keys or banding strips for holding the laminations assembled have had the serious disadvantage of producing a relatively loose core, that is, such cores are not as rigid as is desired for many uses where the cores may be subjected to vibration or other deforming stresses. Moreover, prior modes of assembly have been relatively slow and inelficicnt operations.

It is .a primary object of the present invention to provide a novel mode of core assembly that results in a tight, rigid laminated core having excellent magnetic characteristics.

It is another object of the invention to provide novel apparatus for assembling laminated cores by handing the laminations together with strips of banding material.

A further object of the invention is to provide apparatus of the foregoing character that assembles cores in a manner that insures a tight, rigid core.

Still another object of the invention is to provide apparatus for quickly and economically banding laminations together to form cores.

A further object of the invention is to provide a novel laminated core assembly having excellent magnetic characteristics and which is tight and rigid.

Yet another object of the invention is to provide a novel method of assembling core laminations to form cores.

A further object of the invention is to provide a novel method of applying banding strips to stacks of laminations to form tight, rigid cores.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an elevational view, partially in section, showing a core assembling machine embodying the present invention and engaged in assembling a core;

FIG. 2 is a sectional view of the right half of the machine in FIG. 1 showing the machine at a different stage of operation;

FIG. 3 is a view similar to FIG. 2 showing the machine at still another stage of operation;

FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. .1;

FIG. 5 is a View of the machine taken along line 5-5 in FIG. 1;

'FIG. 6 is an elevational View of a portion of the machine shown in FIG. 1;

FIG. 7 is an elevational View of another portion of the machine shown in FIG. 1;

FIG. 8 is an enlarged elevational view showing fragmen-tarily a part of the structure of FIG. 7;

FIG. 9 is an enlarged sectional view taken along line 9-9 in FIG. 3;

FIG. 10 is an end view showing a core embodying the features of the present invention;

FIG. 11 is an enlarged elevational view of a portion of the edge of the core shown in FIG. 10;

FIG. 12 is an enlarged sectional view taken along line 12l2 in PlG. 2; and

FIG. 13 is a view similar to FIG. 12 showing another form of the structure shown in FIG. '12.

Broadly, the objects of the invention are accomplished by a novel mode of assembling the core laminations, using one or more banding strips to hold the laminations in assembled relations. The laminations are each provided with slots across their peripheral edges. When the laminations are stacked and properly aligned the slots form one or more banding strip receiving grooves that extend from one end of the stack to the other. With the stack in com pressed condition, a strip of handing material is laid in each of the grooves, the ends of each strip being bent over the ends of the stack so that the strip will be in tension when the pressure is released on the stack. To increase the holding power of the strips, the strips are deformed in the grooves, preferably by rolling with a serrated roller, so that the strips engage and are compressed between the respective sides of the grooves. Thus, the strips on an assembled core are in longitudinal tension and in transverse compression. This mode of assembly provides a laminated core having excellent magnetic properties and which is tight and rigid.

Apparatus for assembling the cores according .to this invention includes structure for holding a stack of core laminations in aligned face-toface compressed relation with slots across the edges of the laminations forming one or more banding strip receiving grooves, and structure for supporting a strip of banding material and for laying the strip in the groove upon relative movement between the two structures. The last mentioned structure also includes deforming means, such as a roller, discussed more fully hereinafter, adapted to flatten and deform the strip into holding engagement with the laminations and in the groove. The preferred apparatus uses banding material which is in the nature of a continuous strip, and the apparatus also includes means for forming the strip during banding, as well as a device for severing or cutting the assembled strip from the remainder of the banding material after banding has been accomplished; The cutting device also prepares the end of the remaining portion of the banding strip for the next banding operation. In its 1 preferred form, the apparatus is adapted to carry out each banding operation quickly and automatically and is arranged for mass production of electrical cores, thereby reducing manufacturing costs.

In the drawings, FIGS. 1, 2 and 3 show a preferred form of apparatus embodying the present invention. This apparatus, as illustrated, is adapted to assemble cores used in the stators of electric induction motors. FIG. 1 shows the machine at an early stage during a banding operation; FIG. 2 shows a portion of the same machine at a somewhat later stage of the banding operation and FIG. 3 shows the same portion of the machine at the conclusion of the banding operation.

Generally, the machine shown in FIGS. 1, 2 and 3 includes holding means comprising a movable base member, indicated generally at 11, adapted to receive and hold a stack of laminations 12 in generally aligned, face-to-face relation, and a head member 13 movable toward the base member to compress the stack against the base member 11. The apparatus also has a plurality of banding strip applying devices, indicated generally at 14, four such devices being shown in FIG. 5, mounted in fixed circumferentially spaced positions for applying four banding strips 16 to the stack 12 in a single operation of the apparatus. In addition to the foregoing, the instant apparatus has a similar number of strip forming devices 17 operable during the banding operation to shape the strips 16 prior to application of the strips to the stack. Means such as an hydraulic cylinder mechanism 18, shown in FIGS. -2 and 3, is provided for axially reciprocally movthe base member 11, and the core 12, from a loading position where the core is one one side of the band applying devices 14, through an intermediate position where the band initially engages the stack to a final position where the core is on the opposite side of the devices 14. Means such as a second hydraulic cylinder mechanism, shown at 19 in PEG. 1, reciprocally moves the head member 13 toward the base member 11 and into compressing engagement with the stack 12 at about the intermediate position. Thus, in the present instance the mechanism 18 acts against the force of the mechanism 19 after the head member 13 engages the stack 12. Finally, the machine has four cutoff devices, indicated generally at 21, positioned at the final position mentioned above, for cutting the remainder of the strips from the assembled core.

Before considering in more detail the apparatus for assembling cores, one form of core that is assembled by the apparatus will be described. Thus, FIGS. and 11 show a core 22 for the stator of an electric motor. The shape of the laminations that form the core is apparent in FIG. 10 which shows one end of the core. The laminations, in this instance, are generally annular identically shaped sheets of magnetic material. The inner periphery of each of the laminations if formed to provide a plurality of conventional circumferentially spaced, radially extending pole portions 23, which define slots 24 therebetween, adapted to accommodate the motor field windings. The inner ends of the pole portions define a circular opening adapted to accommodate the rotor of the motor. The outer periphery of each of the laminations is generally circular and is provided, in this instance, with four circumferentially spaced slots extending across the edge of each lamination. When the laminations are stacked in aligned face-to-f-ace relation, as shown, the slots form four banding strip receiving grooves 26.

The grooves 26 are generally rectangular and are preferably shallow compared to their width. The cross sectional shape of one form of groove is shown in FIG. 12. Thus, the groove 26 has a flat bottom wall 27 and perpendicular side walls 28. FIG. 13 shows a modified form of groove having an arcuate bottom wall 2) and side walls 31 which are perpendicular to the chord across the are.

In the banding apparatus heretofore generally outlined, the base member 11 comprises a movable table for carrying the stack of laminations 12 from the loading position to the final position. Since the laminations are of annular form, the base member 11 includes a cylindrical table 32 having an upper annular surface 33 on which laniinations are stacked in face-to-face relation. The diameter of the table 32 is less than the outer diameter of the laminations.

The base member 11 includes means for holding or gripping the iaminations. In the present instance, since the strips of banding material are to be applied to the outer periphery of the stack, the gripping means is a conventional cylindrical arbor mechanism indicated generally at 34, having one end centrally mounted in a bore or cavity 35 in the table 32 (see FiG. 6). The arbor mechanism 34 comprises an axially movable tapered inner member 36 and an outer sleeve 37 formed of relatively movable segments. The outer periphery of the sleeve 37 is substantially cylindrical while its inner periphery is tapered, as shown in FIGS. 1, 2 and 3, to correspond to the taper of the member 36. Thus, axial movement of the member 36 in one direction, toward the table 32 in this instance, expands the segments of the sleeve 37 radially and movement in the opposite direction allows the segments of the sleeve 37 to contract. Axial movement of the sleeve 37 is prevented by radially extending lugs 41 on the inner ends of the segments which form the sleeve 37. The lugs 41 hook under a flange portion 42 which extends radially inwardly and forms part of the surface 33 on the table 32.

The tapered member 36 of the arbor mechanism 1-4 is i actuated toward and away from the table 32 by an bydraulic cylinder mechanism, shown at 38. In this instance, the mechanism 38 is located within the cavity 35 in th table 32 and is connected to the tapered member 36 by a rod 39.

FIG. 6 shows the base member 11 located at the loading position, as previously mentioned, where the laminations are placed on the table 32 around the arbor mechanism 34. At the loading position, the base member 11 rests on the frame or bed 43 of the apparatus (see FIG. 6). To facilitate the alignment of the laminations as they are loaded on the base member 11, the apparatus is provided with a fixed guide 44. The guide 44 is ri idly mounted on the bed 43 and extends outward therefrom along the intended position of one of the grooves 26. The guide 44 has a rib portion 46 located in spaced relation to the arbor mechanism 34- in the intended position of the one groove. The rib portion 46 is dimensioned to have a sliding fit in the groove 26 when the laminations are in the proper rotative position about the sleeve 37 so that their slots will form the banding strip receiving grooves 25.

After a predetermined number of laminations have been loaded on the base member 11 and generally aligned by the guide 44 to form the stack 12, the arbor mechanism 34 expands and frictionally holds or grips the inner surface of the stack 12. Thereafter, the stack is moved by the base member 11 toward the intermediate position by thehydraulic mechanism 18. In the machine shown, this movement is vertical so the hydraulic mechanism 18 is conveniently mounted on the bed 43 of the apparatus below the loading position and is connected to the table 32 by an elongated piston rod 47.

In moving toward the intermediate position, the stack 12 is engaged by portions of the four band-applying devices 14. The band-applying devices 14. are all alike, and are positioned around the path of the stack 12 at positions corresponding to the positions of the grooves 26. Each of the band-applying devices comprises a generally vertical elongated arm 48 having a guide member 45 along its inner edge and a deforming roller 50 on its upper end. These latter elements will be discussed more fully hereinafter. Each arm 48 comprises spaced side portions, one of which is shown at 72 in FIGS. 1, 2 and 3, defining a slot 39 therebetween (see FIG. 7) and each arm is mounted for rotative adjustment at its lower end on a fixed horizontal pivot 49, supported by a frame (not shown) extending upwardly from the bed 43. The axis of the pivot 49 is substantially perpendicular to a radial line extending from the axis of the stack 12 to the particular groove associated with the arm 48. Adjacent the pivot 49, the arm 48 has an horizontally extending portion 51 which extends under a portion 52 of the frame of the apparatus. The portion 51 is provided with an adjustable stop for limiting the counterclockwise movement of the arm, as shown in FIGS. 1, 2 and 3, which, in this instance, is an adjusting screw 53 threaded upwardly through the portion 51 with its upper end in engagement with a plate 54 positioned on the undersurface of the portion 52. To adjustably limit clockwise movement, the arm 48 is provided with an abutment surface 56 at its upper end, facing the portion $2. Another adjusting screw 57 is threaded horizontally through the portion 52 with its end abutting the surface 56. Thus, the two adjusting

screws

53 and 57 cooperate to hold the arm 48 fixed at a predetermined rotative position about the pivot 49.

The guide members 45 of the banding devices, mentioned above, engage the stack 12 as the stack is moved toward the intermediate position, for aligning the stack 12 relative to the rollers 5t prior to application of the banding strips 16. Each of the guide members 45 is elongated and has generally parallel front and back surfaces 53 and 59, respectively (see FIG. 7), and is positioned along the front edge of its associated arm 48 with the front surface 53 facing inwardly for engagement with the stack 12. The upper end of the member 45 is located immediately below the roller 50, and its lower end projects downwardly beyond the lower end of the arm 43 toward the loading position. Along the longitudinal center line of the front surface 58, the member 45 is provided with a longitudinally extending rib 61, which in this instance is a carbide insert. The rib 61 is dimensioned to enter and closely fit within a groove 26. The lower end of the rib 61 is laterally beveled, as at 62, to provide a wedging action on the stack as the rib enters its associated groove if the stack is misaligned with respect to the rollers Sit. Thus, the four guide members 45 cooperate to earn or wedge the stack 12 into alignment for handing.

The guide members 45 are carried by the arms 48 in rigid alignment with the prescribed positions of the grooves 26. Preferably, however, the guide members are movable toward and away from the rigidly held arms 4-8 and are urged away from the arms toward the stack to insureproper engagement with the stack in the grooves 26. To this end, each of the guide members 45 is provided with parallel vertically spaced guide pins 63 (see FIG. 2) projecting outwardly from the back surface 59 through holes 64 in the associated arm 48. The pins have a sliding lit with the holes 64. The holes 64 are counterbored, as at 66 and compression springs 67, encircling the pins 63, are mounted between the arm 48 and the guide member 45 in the counterbores 66 to urge the guide members 45 toward the stack. The pins 63 are each provided with .a head 68 engageable with the arm 48 for limiting the inward movement of guide members. Thus, each guide member 45 is held rigidly aligned parallel to the position of its associated groove and may move toward and away from the stack as required.

Each banding device 14 is adapted to support the end of a strip of handing material in position to engage the stack 12 when the stack reaches the intermediate position. FIG. 1 shows the stack 12 approximately at the intermediate position with the strips 16 initially engaging the stack. It will be noted that the ends of the strips 16 are prebent, as at 69, and hooked over the top end of the stack. To support the strip for this engagement, each of the guide members 45 is provided with a passage 71 extending angularly upwardly through the member 4-5 in the plane of the corresponding groove. A corner 72 is formed at the upper end of the passage 71 where the passage and the rib 61 intersect. The corner 72 acts as a stop on which the prebent end 69 will hook upon movement of the strip backwardly through the passage 71. The strip 16 enters the passage '71 from the slot 89 between the sides 72 of the arm 43. The strip 16 runs on an idler roller 74 mounted in the slot 89 and is fed thereto from the bottom end of the arm.

Immediately after the stack 12 reaches the intermediate position and the prebent end 69 is hooked over the top of the stack, the head member 13 (see FIG. 1) engages the top of the stack and compresses the stack against the base member 11. The head member 13 comprises a circular inverted cup 76 having an annular bottom surface 77 for engagement with the top of the stack. The dimensions of the interior of the cup are such that clearance is provided between the cup 76 and the arbor mechanism 34. The cup 76 is provided with four recessed inserts 78 positioned to clamp the prebent ends 6% against the upper end of the stack 12 when the surface 77 engages the stack. Each of the inserts 78 has a toothed bottom surface 79 spaced from the annular surface 77 sufficiently to accommodate the prebent end 69 of the strip 16. The toothed bottom surface 79 bites into the bent end 69 of the strip to prevent the end from slipping due to tension on the strip.

The head member 13 is moved into engagement with the stack by the aforementioned hydraulic cylinder mechanism 19. The cylinder mechanism is mounted on the frame of the machine above the head member 13 and in axial alignment with hydraulic cylinder mechanism 18.

Thus, it is seen that the

hydraulic cylinder mechanisms

18 and 19, the base member 11 including the arbor mechanism 34, and the head member 13 are all in axial alignment. The mechanism 19 is connected to the cup 76 by a piston rod 81 and exerts a force on the stack until the banding operation is complete. Since the movement of the stack 12 from the loading position to the final position is susbtantially continuous, the hydraulic cylinder mechanism 18 works against the force of the hydraulic cylinder mechanism 19 and is, therefore, correspondingly stronger. Also, it will be noted that the stack 12 remains in compression during the remainder of the banding operation.

As the movement of the stack 12 continues toward the final position, each strip 16 is pulled over the idler roller 74 and through the passage 71 and is progressively laid in its groove 26. As the strip is laid in the groove, the roller 50 laterally deforms the strip into engagement with sides of its groove 26, as illustrated in FIG. 2. In this figure the stack is between the intermediate position and the final position.

One of the principal features of the present apparatus is the roller 56, which is adapted to laterally deform the banding strip 16 in its groove 26 while preventing longitudinal extension of the strip. The width of the roller St) is slightly less than the width of the groove 26, as shown in cross section in FIG. 12, where an enlarged fragment of the periphery of a preferred form of the roller 59 is illustrated in deforming engagement with a banding strip 26, while FIG. 8 shows a peripheral fragment of the roller 50 as seen from the side. As illustrated in FIG. 8, the roller 50 is serrated to provide peripheral teeth 82, and the teeth 82 are crowned to cause the lateral deformation of the banding strip. In the present form, the crown is provided by beveling the side edges of the teeth, as shown at 83 in FIGS. 9 and 12. Between the bevels 83 the teeth 32 are flat, as at 84. The serrations between the teeth are V-shaped, as at 86 in FIG. 8, to strengthen the teeth and to provide sharp transverse leading and trailing edges 87 on the teeth 82.

Each of the rollers Si) is rotatably mounted on an axle 83 in the slot 89 in the upper end of the arm 48 (see FIG. 7) and in alignment to enter its associated groove 26. Being on the upper end of the arm 43, the position of the periphery of the roller 56 is adjustable with respect to the bottom of the groove 26, for optimum deformation of the banding strip 16, by the adjusting screws 53 and 57. As the stack 12 moves from the intermediate position to the final position, the roller 59 enters the groove 26 at the top of the stack and progressively rolls the strip 16 as it is laid in the groove. The crowned teeth 82 laterally deform the strip into engagement with the sides of the groove at longitudinally spaced areas, and the sharp edges 87 on the teeth 32 bite into the strip during rolling and prevent longitudinal extension thereof, so that the deformation of the strip is chiefly lateral. Thus, the strips 16, after being rolled by the rollers 5t), are in compression between the sides of the grooves 226, and frictionally grip the laminations to hold them in assembled relation.

FIG. 13 shows a second form of roller 91 for rolling the banding strips 16 into the grooves 26. This form of roller is generally the same as the roller 5t), but differs from the roller 50 by having teeth 92 which have arcuate' transverse rolling surfaces, such as 93, to provide the crown thereon.

When the bottom of the stack 12 passes the center of the roller 50, engagement of the strips in the grooves is completed and further flattening and lateral deformation of the strips is avoided as the stack moves to the final position where the bottom of the stack is above the top of the rollers 59. To this end, the table 32 is provided with recessed cutoif blocks 94 mounted below the surface 33 of the body 32 and in alignment with the groove 26 in the stack 12. The cutoff blocks 94 have flat top end surfaces parallel to the bottom end of the stack and lo 7. cated in spaced relation thereto. Each cutoff block 94 also has an outwardly facing edge surface 97 generally perpen dicular to the surface 95 and shaped to conform to the shape of the strip prior to deforming by the roller 59. In this instance, the surface 97 is longitudinally corrugated as shown in FIG. 9, and is located radially inwardly relative to the bottom of the groove 26 so that the shape of the strip 16 below the end of the stack 12 will be preserved. When the stack 12 reaches the final position, cutoff blocks 94 are directly opposite the rollers t and the spaces between the surfaces 96 and the bottom of the stack are above the top edges of the rollers 59.

The banding operation is completed by cutting and bending the strips 16 over the bottom end of the stack 12. For this purpose the machine is provided with the cutoff devices 21, each of which is mounted on the frame of the machine above the roller 50, and in position to enter the space between the surface 96 of the insert 94 and the bottom end of the stack 12. Each cutoff device 21 comprises a movable horizontal blade 93 (see FIGS. 1 and 2) and an hydraulic cylinder mechanism 99 for extending and retracting the blade horizontally. The cutting end of the blade is beveled on both the top and bottom sides, as at 1111, to provide a sharp cutting edge. Back of the bevels 191, the sides of the blade may be parallel.

In FIG. 3, the apparatus is shown with the stack 12 at the final position and with the blades 98 in their extended position. It is apparent from this figure that each blade 98 cuts the strip at approximately the middle of the space between the bottom end of the stack and the surface 96 on the cutoif block 94, and at the same time partially bend the strip ends, formed by the cutting, over the bottom end of the stack 12 and over the cutoff block 94. The space between the bottom end of the stack 12 and the cutoff blocks 94 is substantiallyequal to the thickness of the blade and two thicknesses of the strip 16. Thus, with further movement of the blade 98, the sides of the blade press the cut ends of the strip flat against the bottom end of the stack to complete the core assembly and against the surface 96 to provide a prebent end for the subsequent banding operation.

After the strips 16 have been cut, the head member is raised out of engagement with the now assembled core, the arbor mechanism is contracted to release the inside of the core and the base member is returned to the loading position ready to receive the next stack of laminations. This leaves the core resting on the four extended blades 98, from which it is removed by an operator.

By comparing FIGS. 1 and 3, it will be apparent that upon completion of the banding operation, the new prebent ends of the strips 16 are located considerably above the position they should occupy at the beginning of the next banding operation. The strips are repositioned by being partially pulled back through the slots 71 in the guide members 45 by the sets of forming rolls 17 in a manner more fully discussed hereinafter.

The preferred initial form of banding strip is not flat, but is longitudinally corrugated as shown in FIG. 9. The banding strip 16 preferably has two longitudinally extending corrugations and is slightly narrower than the grooves 26 in tack 12. To provide banding strips of this form, the apparatus is provided with a set of forming rolls 17 for each strip, which are adapted to form flat strip stock into the preferred shape. Each set of forming rolls 17 comprises a pair of cooperating rolls 102 and 103 (see FIG. 2) rotatably mounted respectively on axles 104 and 166, mounted in a carriage 107 comprising a pair of spaced plates. The carriage 107 is movably mounted on a fixed member 1118 forming part of the frame. In the present instance, the member 108 is provided with a longitudinally extending groove or way 109 in which is disposed a rib portion or key 111 of the carriage 107. The line connecting the centers of the rolls 102 and 194 is aligned perpendicular to the longitudinal axis of the keyway. The keyway extends generally toward the slot '71 in the guide member 45, so that the carriage is movable toward and final position.

or away'from the guide member in the'dir-ection of the trip. A fixed stop 112 is provided at the upper end of the way 1%9 for engagement by the carriage 137 and an adjustable stop 113 in the form of a screw is provided at its lower end. Also, a compression spring 114 (see FIG. 1) is interposed between the stop 112 and the carriage to urge the carriage away from the stop 112. A shown in FIGS. 2 and 3, the strip 16 enters the forming rolls as flat stock from one side of the roll 132, and extends from the rolls under the idler roller 73 and into the slot 71.

From the above arrangement it is seen that the initial pulling force on the strip 16 exerted by the upward movement of the base member 11 also pulls the forming rolls 17 upwardly until the carriage 167 engages the stops 112. Thereafter the pulling force draws the flat stock through the rolls 17, thereby forming a length of the strip 16 sufficient for one complete subsequent banding operation. After the banding operation, when the base member 11 disengages the assembled core, the weight of the set of rolls 17 together with the force of the spring 114 is sufficient to move the carriage 107 away from the stop 112 and into engagement with the stop 113. This movement pails the strip back through the slot or passage 71 until the prebent end is positioned at the corner '72 of the guide rib 61.

The sequence of operation of the above-described apparatus is as follows: With the base member 11 at the loading position, the laminations are loaded in generally aligned relation on the base member to form the stack 12. Next, the arbor mechanism 34 is expanded to frictionally grip the inside of the stack. Then the cylinder mechanism 18 forces the base member 11 toward the banding devices and the final position. As the stack moves up, portions 61 on the four guide members 45 enter the grooves 26 and, if necessary, shift the stack into alignment and thereafter hold the stack aligned relative to the rollers '59. When the top of the stack 12 reaches the upper ends of the guide members 45, referred to above as the intermediate position, the prebent ends 69 of the banding strips 16 book over the top of the stack. The head member 13 then engages the stack, the en gagement axially compressing the stack and clamping the prebent ends of the strips 16 to the end of the stack. Further upward movement of the stack pulls the strips through the slots 71, lifting the sets of forming rolls into abutment against the stops 112, and thereafter also pulls the strips through the set of forming rolls 17. At the same time the strips are being progressively laid in the grooves 26 and the rollers 50 laterally deform the strips into engagement with the sides of the grooves 26. The deforming continues until the bottom of the stack passes the center of the rollers 50. Thereafter, deforming the strips by pullling continues until the bottom of the stack is above the top of the rolls and reaches the Further upward movement of the stack then stops and the cutoff devices 21 are actuated to exend their blades 93, thereby cutting the strips and bending the ends thus formed over the bottom of the stack and over the cutoff blocks 94, respectively. This completes the banding operation and provides prebent ends on the strips for the next banding operation.

Once the banding operation is complete, the head mem ber 13 is raised to disengage the assembled core and the arbor mechanism 34 is contracted to release the inside of the core. The base member 11 is then returned to the initial position ready to receive a succeeding stack of l-aminations, leaving the core resting on the extended blades 98. As the base member is returned, the sets of forming rollers 17 pull the strips 16 back through the slots 71 until their new prebent ends are hooked over the sharp edges 72 and are thus positioned for the next operation. After the core is removed from the blades 98, the blades may be retracted and the machine is ready for the next banding operation.

Another important aspect of the invention is the core formed according to the foregoing. In the preferred form of the core shown in FIGS. 10, 11 and 12, the grooves 26 may be of the shape shown in FIG. 12, previously described. The stack is held in assembled relation by the four elongated banding strips 16 mounted in the grooves 26. As shown in FIG. 11, the strips have longitudinally spaced, generally convex depressed areas 116 extending transversely of the strips, the strips thickening at their side edges. Between the depressed areas 116 the strips 16 have areas 117 that are longitudinally corrugated. The bottom surfaces of the strips 16 are substantially flat and tight against the bottom wall 27 of the groove. Moreover, the strips 16 are laterally compressed between the sides of the grooves. Both ends of each of the strips are bent over the ends of the stack and the strips are in longitudinal tension. The core 22, held assembled in this manner, is not only tight and rigid, but also has excellent magnetic characteristics.

FIG. 13 illustrates a slightly modified form of the core 22, in which grooves have arcuate bottom walls 29. Because of the mode of rolling the strips into the grooves, the strips, indicated at 113 in this instance, assume the generally arcua-te shape shown and have generally convex depressed areas alternating with longitudinally corrugated areas, .as in the first form. It is apparent from the drawing that the center portion of the strip is in an over-center relation with respect to its side portions, so that vibrations and other stresses in the core tend to increase the holding effect of the strips on the stack.

From the foregoing it is apparent that the invention provides a novel method of core assembly and novel apparatus for carrying out the method to produce a new form of core for electrical machines. The apparatus assembles tight or rigid laminated cores quickly and economically, using banding strips to hold the laminations in assembled relation. The novel cores thus formed have excellent magnetic characteristics.

Although the invention has been described in connection with certain specific structural embodiments, it will be understood that various modifications and equivalent structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

We claim:

1. Apparatus for banding a stack of slotted core laminations to form a core, said apparatus comprising means for holding the laminations in rigidly aligned stacked relation with their slots forming a banding strip receiving groove, a banding device for applying a strip of banding material to the stack in the groove, and means for moving said holding means together with said stack from a loading position on one side of said banding device to a final position on the other side of said banding device in a direction parallel to the groove, said banding device comprising an arm, an elongated guide member mounted on said arm and having a portion aligned to project int-o the groove, said device being adapted to support the strip and to lay the strip in the groove, and a roller mounted on said arm adjacent the end of said guide member to follow said portion through the groove, said roller being adapted to deform the strip into engagement with the groove, whereby to lock the laminations together, said guide member having a passage for carrying the strip, said passage being in the plane of the groove and extending angularly through the guide member to the end of the guide member adjacent the point of engagement of the roller with the strip.

2. Apparatus for banding a stack of slotted core laminations to form a core, said apparatus comprising means for holding the laminations in rigidly aligned stacked relation with their slots forming a banding strip receiving groove, a. banding device for applying a strip of handing material to the stack in the groove, and means for moving said holding means together with said stack from a loading posi- :tion on one side of said banding device to a final position on the other side of said banding device in a direction parallel to the groove, said banding device comprising an arm, an elongated guide member mounted on said arm and having a portion aligned to project into the groove, said device being adapted to support the strip and to lay the strip in the groove, and a roller mounted on said arm adjacent the end of said guide member to follow said portion througth the groove, said roller being adapted to deform the strip into engagement with the groove, whereby to lock the laminations together, said arm being mounted at one end on a pivot for swing movement toward the groove, said roller being mounted on the other end of said arm, and means for adjusting the pivotal position of said arm and for rigidly holding said arm at said position, to adjust the pressure exerted by said roller on the strip.

3. Apparatus for banding a stack of slotted core laminations to form a core, said apparatus comprising holding means for receiving and holding the laminations in aligned stacked relation with the slots in the laminations forming a banding strip receiving groove, banding means for applying a strip of banding material to the stack in the groove, said two means being movable relative to each other in a direction parallel to the groove, said banding means having a guide member in alignment with the groove to enter the same upon said relative movement, said banding means being adapted to support a bent free end of the strip in a position adjacent the end of said member to hook the bent end over one end of the stack and to thereafter progressively lay the strip in the groove, said banding means also having means for deforming the strip into engagement with the groove, and means for bending the strip inwardly over the op posite end of the stack and for cutting the strip, thereby leaving a bent end of the strip for the next banding operation.

4. Apparatus for banding a stack of slotted core laminations to form a core, said apparatus comprising a base member adapted .to receive the laminations in generally aligned stacked relation with their slots forming a banding strip receiving groove, banding means for applying a strip of banding material to the stack in the groove, means for moving said base member from a loading position on one side of said band applying means through an intermediate position where the band engages the stack and then to a final position in the opposite side of said banding means in a direction parallel to the groove, said banding means having a guide member adapted to project into the groove as said base member moves from said loading position to said intermediate position, said guide member and said base member coacting to further align and to preserve the alignment of the laminations, a head member facing said base member, and means for moving said head member toward said base member to engage the stack at said intermediate position and compress the stack against said base member, said banding means also having means for deforming the strip into engagement with the groove as said base and head members and the stack move from said intermediate positron .to said final position, whereby to lock the laminatrons together; said guide member comprising an elongated body portion and a longitudinally extending rib positioned on the body portion to enter the groove, the width of said rib being substantially equal to the width of said groove; said rib comprising a carbide insert having an end projecting toward said loading position and beveled to cam the laminations into alignment as the base member and the stack move toward said intermediate position.

5. Apparatus for banding a stack of slotted core laminations to form a core, said apparatus comprising a base member adapted to receive the laminations in aligned stacked relation with their slots forming a banding strip receiving groove, band applying means adapted to sup port a :bent free end of a strip of banding material in ill position to hook the bent end on one end of the stack, means for moving said base member from a loading position on one side of said band applying means to an intermediate position where the bent end hooks on the one end of the stack and then to a final position on the opposite side of said band applying means in a direction parallel to the groove, a head member facing said base member, means for moving said head member toward said base member to engage the stack at said intermediate position and to compress the laminations between said members, said head member also having means for pressing and holding the bent end of the strip against the one end of the stack, said band applying means having means for deforming the strip into engagement with the groove as said holding means and the stack of laminations move from said intermediate position to said final position, and means positioned at said final position for bending the strip over the opposite end of the stack and for cutting the strip to complete the banding, thereby leaving a new end of the strip bent for the next banding operation.

6. Apparatus according to claim 5, in which said base member has a cut-off block positioned in alignment with the groove and spaced from the opposite end of the stack, and said bending and outing means comprises a blade movable against the strip parallel to the laminations and into the space between the opposite end of the stack and said cut-off block.

7. Apparatus according to claim 6, in which said cutoff block has a fiat end surface generally parallel to and 12 facing the opposite end of the stack and an edge surface generally perpendicular to said end surface with the strip adapted to extend along said edge surface when said base member is at said final position, said edge surface being shaped to conform to the shape of the strip prior to deforming for preserving the shape of the strip.

References (listed by the Examiner UNITED STATES PATENTS Re. 18,968 10/33 Willers 29-1635 1,538,187 a 5/25 Herrick 29-155 1,978,035 10/34 Thom 93-1 2,199,623 5/40 Elsey 153 2,210,749 8/ Brugmann 29-522 X 2,226,398 12/40 Cristiano et a1. 153 2,313,228 3/43 Dornonkos 29-522 2,478,316 8/49 Potter 310-217 2,610,225 9/52 Korski 29-155.6l X 2,706,331 4/55 Bartelheim et al. 29-203 2,711,008 6/55 Smith 29-155.5 2,774,001 12/56 Riedel 310-217 2,809,421 10/57 Dowse et a1. 29-200 2,823,016 2/ 58 Greer 29-522 2,850,795 9/58 Nichols et al 29-203 2,908,965 10/59 Platt 29-155.5

JOHN F. CAMPBELL, Primary Examiner.

MILTON HERSHFIELD, WHITMORE A. WILTZ,

FRANK E. BAILEY, Examiners.

Claims

4. APPARATUS FOR BANDING A STACK OF SLOTTED CORE LAMINATIONS TO FORM A CORE, SAID APPARATUS COMPRISING A BASE MEMBER ADAPTED TO RECEIVE THE LAMINATIONS IN GENERALLY ALIGNED STACKED RELATION WITH THEIR SLOTS FORMING A BANDING STRIP RECEIVING GROOVE, BANDING MEANS FOR APPLYING A STRIP OF BANDING MATERIAL TO THE STACK IN THE GROOVE, MEANS FOR MOVING SAID BASE MEMBER FROM A LOADING POSITION ON ONE SIDE OF SAID BAND APPLYING MEANS THROUGH AN INTERMEDIATE POSITION WHERE THE BAND ENGAGES THE STACK AND THEN TO A FINAL POSITION IN THE OPPOSITE SIDE OF SAID BANDING MEANS IN A DIRECTION PARALLEL TO THE GROOVE, SAID BANDING MEANS HAVING A GUIDE MEMBER ADAPTED TO PROJECT INTO THE GROOVE AS SAID BASE MEMBER MOVES FROM SAID LOADING POSITION TO SAID INTERMEDIATE POSITION, SAID GUIDE MEMBER AND SAID BASE MEMBER COACTING TO FURTHER ALIGN AND TO PRESERVE THE ALIGNMENT OF THE LAMINATIONS, A HEAD MEMBER FACING SAID BASE MEMBER, AND MEANS FOR MOVING SAID HEAD MEMBER TOWARD SAID BASE MEMBER TO ENGAGE THE STACK AT SAID INTERMEDIATE POSITION AND COMPRESS THE STACK AGAINST SAID BASE MEMBER, SAID BANDING MEANS ALSO HAVING MEANS FOR DEFORMING THE STRIP INTO ENGAGEMENT WITH THE GROOVE AS SAID BASE AND HEAD MEMBERS AND THE STACK MOVE FROM SAID INTERMEDIATE POSITION TO SAID FINAL POSITION, WHEREBY TO LOCK THE LAMINATIONS TOGETHER; SAID GUIDE MEMBER COMPRISING AN ELONGATED BODY PORTION AND A LONGITUDINALLY EXTENDING RIB POSITIONED ON THE BODY PORTION TO ENTER THE GROOVE, THE WIDTH OF SAID RIB BEING SUBSTANTIALLY EQUAL TO THE WIDTH OF SAID GROOVE; SAID RIB COMPRISING A CARBIDE INSERT HAVING AN END PROJECTING TOWARD SAID LOADING POSITION AND BEVELED TO CAM THE LAMINATIONS INTO ALIGNMENT AS THE BASE MEMBER AND THE STACK MOVE TOWARD SAID INTERMEDIATE POSITION.