US2682179A - Intermittent drive for presses - Google Patents

Description

June 29, 1954 R. A. FREEMAN INTERMITTENT DRIVE FOR PRESSES Filed Nov. 30, 1949 R E i 3 w a A INVENTOR Raymond A. Freeman MAJ BI /M A ftgrney:

Patentecl June 29, 1954 INTERMITTENT DRIVE FOR PRESSES Raymond A. Freeman, Hudson, N. Y., assignor,

by mesne assignments, to Emhart Manufacturing Company, a corporation of Delaware Application November 30, 1949, Serial No. 130,330

Claims. 1

This invention relates to improvements in rotary indexing mechanisms, and in particular to improvements in dial feed mechanisms for in: termittently rotating Work pieces from one position to another in timed relation, for example in synchronism with the strokes of a punch or stamping press.

Such presses are used for performing successive operations at different stations of work supporting mechanism, such as for notching or slotting the circular laminations that make up electric motor rotors or stators. The blanks for rotor laminations are usually disk shaped and the slots or notches are made in their peripheral edges. Blanks for stator laminations are generally ring shaped and the slots or notches are made in their inner edges. In either case the blank is mounted upon the punch press and is intermittently rotated through a predetermined angle for every stroke of the punch, so that a notch or slot is made by the punch for every stroke, the blank being stationary during the actual punching operation. The punch press in this type of operation is usually automatically stopped after the notches have been stamped out during a full 360 degree rotation of the blank, after which the completed blank is replacedby a new one.

Presses of foregoing types are well known in the prior art, and one of the major problems is to construct them so that they can be operated at high enough speeds as to make them turn out the maximum number of completed work pieces per unit of time. Many of the problems have been satisfactorily solved, such as the mechanism for starting and stopping the press rapidly when a new blank has been mounted and when it has been completed. However, one of the major problems remaining has been the provision of an intermittent drive for the work feed, so that it could be operated as fast as the rest of the press is capable of operating. Since it must be stationary during the time that the operation is performed on the work piece, it can be shifted only during the remaining interval of the cycle of the reciprocation. In the past, the customary drive for the feed has included friction couplings and Geneva movement or ratchet and pawl mechanism or the like to provide the intermittent motion from continuously rotating press drive to the feed mechanism. The friction couplings, Geneva and ratchet and pawl mechanisms are limited to the present conventional operating speeds. They do not provide a suitable intermittent motion drive for optimum speeds of the presses presently available. By their very nature these mechanisms have fixed characteristics of acceleration and deceleration which limit their practical speeds of operation well below those attainable by the press mechanisms.

By my present invention I have been able to speed the feed mechanisms substantially above the speeds of prior feeds thereby materially increasing press outputs. This I have accomplished by use of a novel worm drive for the feed mechanism in which the worm is so shaped that it imparts the desired intermittent feed to the work pieces with controlled acceleration and deceleration to minimize the stresses and strains of operation. In that preferred embodiment of my invention an anti-friction worm gear or follower engages the worm and drives the work pieces intermittently through a set of gears which can be changed to provide selected angles of rotation to the work piece in accordance with the work to be performed. The acceleration and deceleration of the associated mechanism is accomplished smoothly with minimum vibration and wear, and the wear is imposed on readily replaceable elements of the follower. As a result the operation of the presses can be at much higher rates-of speed, thereby reducing the time and costs of producing finished work pieces.

It is therefore a primary object of the invention to provide a new and improved intermittent press feed mechanism.

Another object is the provision of a press having an improved positive intermittent drive for the work piece, wherein the shifting of the work piece from one position to another may be done automatically at high speeds in timed relation with the press strokes, and wherein interchangeable gears in the drive permit full adjustment in accordance with the number of operations to be performed in a feed cycle.

In the conventional notching presses of the prior art, when a change in the number of notches is made, it is necessary to change the index ring of the dial feed fixture. This requires stocking of hardened and ground'rela-tively expensive rings individual to each notch number to be punched and the change requires a substantial amount of labor and time during which the press is out of operation. Such changes are accordingly costly in equipment, labor and in loss of production time. In my present invention I eliminate the need for index rings on the press, and their attendant disadvantages, by providing a novel mechanism in which the number of notches are varied by an inexpensive and readily changed pinion gear,-

It is accordingly a further object of the invention to provide a novel mechanism for varying the number of notches made in a work piece in notching presses.

Other objects will become apparent as the description proceeds in connection with the accompanying drawings, wherein:

Figure l is a top plan view, partly in section, of one illustrative embodiment of the invention.

Figure 2 is a vertical sectional view substantially along the line 2-2 of Figure 1.

Referring to Figures 1 and 2, at It) is shown the fixture base of a punch press, which is suitably mounted by means not shown, upon a body frame ll (Fig. l). The fixture has a substantially rectangular vertical opening [2 therethrough, the vertical centerline of the punch (not shown) being indicated at M. A ring gear [5 having outer peripheral gear teeth It is supported by the fixture base for rotation in a horizontal plane. The inner wall of the ring gear has a continuous groove or track I! which receives the outer races of a series of ball bearing assemblies [8 which are mounted by their inner races on studs [9 that are threaded into the top of the fixture base [0. Thus ring gear i is free to rotate in a horizontal plane about an axis displaced from the centerline M of the punch, and a suitable holder for the blank to be punched may be attached to the ring in any suit able manner. This particular illustrated embodiment is intended particularly to support motor stator lamination blanks so that they may be internally notched as the ring gear to which the blank is attached is rotated through a predetermined angle after each working stroke of the punch. The structure by which the fixture base ill is shifted with respect to the body frame H and the punch centerline I4 is conventional, and for that reason is not shown here.

Ring gear i5 is intermittently rotated in timed relation with the strokes of the punch by means now to be described. The body frame I I has secured to it by a pair of bolts 22, a bracket 2| having spaced legs 23 and 24 within which are fixed in any suitable manner the outer races of a pair of ball bearing assemblies 25 and 26. A hollow shaft 21 has a tight fit in the inner races so as to rotate therewith, and integral with the hollow shaft but exterior of the bracket is a clamp block formed by longitudinally slitting one side of the block at 28. A driven shaft 29 has a sliding fit in the bore of the hollow shaft 27 and the clamp block, but it is securely clamped in any adjusted longitudinal position by means of studs 32 which are threaded into the clamp block and which bridge the slit 23. Keyed to the hollow shaft 2'! by a key 33 is a chain sprocket 34, and a pair of sprocket chains 35 driven by the punch crank-shaft (not shown) rotate the sprocket 34 and shaft 29 in the illustrated embodiment, at the speed of the press'shaft.

A two piece housing indicated generally at 36 has its sections 31 and 38 rigidly secured together by vertically spaced pairs of studs 39 and 40. The section 31 has a pair of vertical ears 43 and 44 each having a pair of horizontal slots 45 and 4G therethrough, and pairs of studs 41 and 48 passing through these slots and threaded into the fixture base IO- secure the housing to the fixture base. It will be understood that only one slot 45 and one slot 46 are shown in Fig. l but that the other slot of each pair is vertically spaced therefrom, s'o that-actually there are two studs 41 and two studs 48. In a similar manner,

while only two studs 39 and 49 are shown to hold the housing sections 31 and 38 together, the other stud of each pair is vertically spaced therefrom. The slots 45 and 46 in the ears 43 and 44 permit adjustment within limits of the housing 38 with respect to the bracket 2!, for a purpose to be described. This adjustment takes place by movement of housing 36 parallel to the axis of shaft 29. In order to extend the range of this adjustment the fixture base is provided with a row of horizontally spaced tapped holes 5| for each stud 41 and 48, so that if enough adjustment is not provided by the slots 45 and 46, the studs can be removed and inserted into the next adjacent tapped holes.

The shaft 29 is also mounted for rotation in the housing 36 by a pair of ball bearing assemblies 4s and 59 which have their outer races clamped between shoulders in the housing section 38 and retainers 53 and 54 secured to the section. Shoulders 55 and 256 on the shaft 29 locate the shaft in fixed axial position with respect to the bearing assemblies and housing section 33. A hardened and ground worm 5'1 is keyed to the shaft 2:! by a key 58 (Fig. 2) and its axial position on the shaft is determined by a pair of threaded collars 59 and $6 on threaded portions El and B2 of the shaft 29 adjacent the ends of the worm, these collars being clamped against the ends of the worm. Thus tolerances in the manufacture of the assembly may be large, yet the exact axial position of the worm 51 on shaft 29 and within the housing 36 can be set within very close limits.

A frictionless worm follower or gear is indicated generally at 65 in Figure I. It has a main body portion 66 rotatable about a vertical axis by means of integral upper and lower shafts 61 and 68 mounted in readily removable and replaceable ball bearing assemblies 59 and 10 in the housing section 3'5. This housing section 31 is split in a horizontal plane through the shaft 29 to form upper and lower parts "H and 12 (Fig. 2) rigidly secured together by bolts '53 (Fig. 1), there being a cavity 74 formed by the assembled upper and lower parts, to receive the body portion 68 of the follower 65. Six equiangularly spaced studs "H are threaded radially into the body portion 66, each stud securing the inner race of a ball bearing assembly 18 to the body portion. Spacer washers I9 keep the bearing assemblies slightly spaced from the bottom portion 66, and set screws 82 lock the studs i? in place. The hardened outer races 78 embrace a thread of the hardened and ground worm as illustrated in Figure 1, preferably with a pre-load so that the rotating worm drives the worm follower or gear 65 without back lash. The shaft 61 on the follower 65 protrudes upwardly above the housing section 3'! and carries a pinion gear 84 that meshes with the ring gear E5 to rotate it and the motor stator lamination blank carried by the blank holder attached to the ring gear. That portion of the shaft 61 carrying the pinion gear 84 has several radial slots 85 therethrough, and a stud 36 is threaded axially into the upper end of the shaft 671, the bottom of the head of the stud forming a conical wedge, so that when the stud is screwed down tightly it secures the pinion gear in any preselected angular position upon the shaft 6?.

As best shown in Figure 1, the thread of the worm does not form a true helix but has a dwell portion 81 which, in the illustrated embodiment, is degrees in length. Thus this dwell portion 81 will be engaged by the follower 65 during one quarter of every revolution of the shaft 29, and during this period the ring gear l5 will become stationary. It isduring this period that the punch in a notching press strikes and punches out the desired notch in the motor lamination blank and is again withdrawn. During the re- -maining 270 degree rotation of theworm 51 and shaft 29 the ring gear advances the blank to the next position for a punching operation. Since the driven'shaft 29 is driven by the punch crankshaft, the intermittent rotation of the ring gear I5 will always be in timed relation with the strokes of the punch, irrespective of its speed.

The intermittent drive provided by the worm 51 with its dwell portion 81 furnishes a positive intermittent drive to the ring gear at speeds heretofore unavailable in the operation of such presses. Thus the notching press referred to can be operated at any speed within its normal practical limitations, and a reduced speed need not be used to allow the intermittent feed mechanism to function properly.

The construction also provides a full range of adjustment to vary the number of notches without use of conventional index rings, and to permit the notching at different diameters.

To vary the number of notches, the pairs of studs 41 and 48 are loosened to permit adjustment of the housing 36 toward or away from the bracket 2i so as to permit substitution of the proper size of pinion gear 84 to drive the ring gear 15 atthe desired speed ratio. If the slots 45 and 46 do not permit sufficient adjustment, then the pairs of bolts 41 and 48 are withdrawn and threaded into another set of tapped holes 51. In any case, before shifting the housing 36, the studs 32 which clamp the hollow shaft 21 to the driven shaft 29 at the slit 28 are loosened, to permit axial movement of the shaft 29. After the housing 36 is secured in its correct adjusted position, the studs 32 are again tightened to secure the shaft 29 to the hollow shaft 21. Suitable axially extending aligning marks are provided on shaft and retainer 53 to maintain proper timing between the intermittent movements of ring gear l5 and the strokes of the punch. If necessary, timing adjustments are made by loosening the stud 8B which locks the pinion gear 84 to the shaft 61, aligning said marks and then tightening stud 86. This alignment is made by rotating the shaft 29 while the clamping studs 32 in the hollow shaft 21 are loosened, as will be understood. It will accordingly be seen that the need for conventional index rings on notching presses is eliminated by my invention.

To vary the diameter at which notching occurs, studs 32 are loosened and the fixture I is shifted with respect to center line l4 of the press by the conventional fixture adjusting screw (not shown) to notch at the desired diameter and studs 32 are then tightened.

Once the worm and the worm gear or follower 65 are properly adjusted in the housing 36 they need not be disturbed. The axial adjustment of worm 51 provided by the threaded collars 59 and Gil assures that the dwell portion 81 can be located in the same vertical plane as the axis of the follower 65.

The invention permits a much higher speed of practical operation, and provides a positive drive without friction coupling or brake mechanism (such as is used in conventional notching press drives) and in which there is substantially no appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a machine, a motion transmitting assembly comprising a constantly driven shaft, a worm on said shaft, a worm follower engaging said worm, and a first gear connected to said worm follower, a second gear meshed with said first gear and driven thereby and mounted for rotation about an axis fixed relative to the axis of said shaft, said assembly being movably mounted as a unit to vary the distance between the axes of said first and second gears whereby at least one of said gears may be changed to vary the driving ratio, and a bearing for said shaft spaced from said worm, said bearing including a sleeve slidably journalling said shaft and a coupling operable to secure said shaft to said sleeve for rotation therewith.

2. In a machine, a base member, a gear mounted on said base for rotation about a fixed axis, a uniformly driven member mounted in fixed relation to said base for rotation about an axis lying in a plane normal to the axis of rotation of said gear, a motion transmitting assembly operatively interconnecting said uniformly driven member and said gear for imparting intermittent rotary movement to said gear comprising a housing securable to said base member at any one of a plurality of positions in a rectilinear path parallel to the axis of rotation of said uniformly driven member, a shaft journalled in said housing coaxial with said uniformly driven member, said shaft and said uniformly driven member being coupled for conjoint rotation and free relative axial movement, an intermittent motion mechanism including a driving member fixed to said shaft and a driven member journalled in said housing for rotation about an axis spaced from and normal to that of said shaft, and a second gear detachably secured for coaxial conjoint rotation with the driven member of said intermittent motion mechanism in constant mesh with the first said gear whereby said assembly can be shifted as a unit to various positions along said rectilinear path relative to said first gear and gears of various sizes substituted for said second gear to vary the driving ratio between said uniformly driven member and the first said gear.

3. In a machine, a support, a constantly driven shaft journalled in said support, an intermittent motion mechanism comprising a driving member fixed to said shaft and a driven member in engagement therewith journalled in said support for rotation about an axis spaced from and normal to that of said shaft, a first gear connected to said driven member of said intermittent motion mechanism and driven thereby, a base member to which said support is securable in any one of the plurality of positions lying in a rectilinear path parallel to the axis of said shaft, 9. second gear mounted upon said base member for rotation about a fixed axis parallel to the axis of rotation of said first gear when said support is so secured and in constant mesh with said first gear to be driven thereby, the assembly formed by said support, said shaft, said intermittent motion mechanism, and said first gear being movable as a unit in such rectilinear path to vary the distance between the axes of said first and second gears whereby at least one of said gears may be changed to vary the driving ratio therebetween, and a uniformly driven member mounted for rotation in a fixed position relative to said base member coaxial with said shaft and so coupled to said shaft for conjoint rotation therewith and free axial relative movement thereto.

4. In a machine, an intermittent motion transmitting assembly comprising a constantly driven shaft, a mutilated helical worm fixed on said shaft, a worm follower constantly engaged with said mutilated helical worm and intermittently rotated thereby, and a first gear connected to said worm follower; a second gear meshed with said first gear and mounted for rotation about an axis fixed relative to the axis of said shaft, said assembly being movably mounted as a unit in a path parallel to the axis of said shaft to vary the distance between the axis of said first and second gears whereby at least one of said gears may be changed to vary the driving ratio therebetween, and a uniformly driven member mounted for rotation coaxial with said shaft in a fixed position relative to the axis of rotation of said second gear and coupled to said shaft for conjoint'rotation therewith and free relative axial movement thereto.

5. In a machine, a motion transmitting assembly comprising a constantly driven shaft, a worm on said shaft, a Worm follower engaging said worm, and a first gear connected to said worm follower; a second gear meshed with said first gear and mounted for rotation about an axis fixed relative to the axis of said shaft, said assembly being movably mounted as a unit in a path parallel to the axis of said shaft to vary the distance between the axis of said first and second gears whereby at least one of saidgears may be changed to vary the driving ratio therebetween, and a uniformly driven member mounted for rotation coaxial with said shaft in a fixed position relative to the axis of rotation of said second gear and coupled to said shaft for conjoint rotation therewith and free axial movement relative thereto.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,098,371 Donnelly June 2, 1914 1,297,462 Hallenbeck Mar. 18, 1919 1,349,958 Head Aug. 17, 1920 1,709,439 Morris Apr. 16, 1929 1,720,971 Schweich July 16, 1929 1,932,571 Blood Oct. 31, 1933

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