US3477560A - Automatic accumulating down elevator - Google Patents

Description

Nov. 11, 1969 R. BROSER AUTOMATIC ACCUMULATING DOWN ELEVATOR 3 Sheets-Sheet 1 Filed Dec. 8, 1967 RICHARD BROSER ATTORNEYS Nov. 11, 1969 v R. BROSER 3,477,560

AUTOMATIC ACCUMULATING DOWN ELEVATOR Filed Dec. 8, 1967 3 Sheets-Sheet 2 INVENTOR 52) 36 RICHARD BROSER 3 BY egl 16 2. Liam ATTORNEYS Nov. 11, 1969 R. BROSER AUTOMATIC ACCUMULATING DOWN ELEVATOR" 3 Sheets-Sheet 5 Filed Dec. 8, 1967 FIG. 5

INVENTOR RICHARD BRO SEIR BY 6%, M, V' 6-12 ATTORNEYS United States Patent O U.S. Cl. 198-218 2 Claims ABSTRACT OF THE DISCLOSURE Mechanism is provided for conveying workpieces vertically downwardly in discrete increments between adjacent holding stations. A vertically reciprocating transfer bar has a plurality of vertically spaced lift fingers mounted thereon which selectively remove a workpiece from a given holding station and transfer it downwardly and deposit it at the next adjacent lower holding station. Detector arms at each holding station sense the presence or absence of a workpiece of the respective station. If a holding station is vacant, the corresponding detector arm will automatically activate all the appropriate lift fingers to cause all upwardly located workpieces to simultaneously advance one holding station upon a single reciprocation of the transfer bar.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A through 1D illustrate a portion of the workpiece lifting and holding mechanism shown in four successive stages of a single stroke cycle of the transfer bar, wherein FIG. 1A illustrates the bottom of the stroke, FIG. 1B illustrates the point on the upward stroke at which the lift fingers begin to be cammed to their operative position, FIG. 1C illustrates the point near the top of the upward stroke at which the lift fingers have picked up a workpiece in preparation for carrying it downward to the next empty station, and FIG. 1D illustrates a point on the downward stroke just prior to the depositing of the workpiece at an empty work station.

FIG. 2A and 2B illustrate the transfer bar and rest arm control bar portions of the structure, with FIG. 2A corresponding to the point in the stroke illustrated in FIG. 1B, and FIG. 2B illustrating the point in the stroke corresponding to FIG. 1C.

FIG. 3 is a cross-sectional plan view of the mechanism viewed in the direction of arrows 3--3 of FIGS.

1B and 2A.

FIG. 4- is a partially fragmented perspective view of a portion of the mechanism.

FIG. 5 is a fragmented side view illustrating the means for retracting the lift fingers, viewed in the direction of arrows 5--5 of FIG. 1A.

DESCRIPTION OF THE STRUCTURE The apparatus of this invention generally comprises a' supporting frame (FIGS. 3 and 4) which is generally E-shaped in plan view. The vertically oriented transfer bar 12 is mounted for vertical reciprocating movement, being guidably supported by a dovetail interlock with the guide column or middle leg 14 of frame 10. Transfer bar 12 is caused to reciprocate vertically by a motor schematically illustrated at 15 in FIG. 2A. Other types of reciprocating devices such as a hydraulically operated cylinder may be employed.

Vertically spaced lift fingers 16a, 16b, and 16c, are mounted on pivot pins 18 secured to transfer bar 12. These lift fingers are spaced at a distance equal to the length of incremental travel of the workpieces as they progress downward from one holding station to the next. The lift fingers are each provided with a slot 20 which cooperates with a stop pin 22 secured to transfer bar 12 to control the limit of pivotal movement with respect to the transfer bar.

Each of these lift fingers comprises a pair of identical elements (see FIGS. 3 and 4) provided with a nest or notch 24 for cradling a workpiece. On one side of each lift finger is a follower plate 26 for a purpose to be described below.

A trip arm 28 is pivotally secured to each lift finger by a pin 30. Each of these trip arm segments has a longitudinal bore at each end to slidably receive a trip arm guide pin 32. Guide pin 32 permits the individual trip arm segments to move away from each other longitudinally without losing their alignment.

Rest arms 34a, 34b, 34c, and 34d, are each pivotally secured to frame 10 by their respective pivot pins 36. Each rest arm is generally U-shaped in plan View (FIG. 3), with a connecting bar 38 joining two identical arms each provided with a nest 40 for cradling a workpiece. These rest arms function as holding stations for temporarily supporting a workpiece between its advancing movements. An unoccupied holding station is constructed so that gravity tends to cause it to pivgt to the position shown at 34d in FIG 1C, for example. A pair of workpieces 42a and 420 are shown in FIGS. 1 and 2 as supported at the holding stations defined by rest arms 34a and 340, the additional weight of the workpiece causing the associated rest arm to overcome the above described tendency.

Also pivotally mounted on frame 10 is a plurality of workpiece detector arms 44a, 44b and 440, each mounted on its respective pivot pin 46. Each of these detector arms is provided with an inwardly directed cam pin 48 which engages lift finger follower plate 26 as described below. Upward or clockwise movement of these detec tor arms is limited by a stop pin 50 secured to frame 10 adjacent each arm. These detector arms are constructed so that they will normally assume the position of arm 44b in FIG. 1A, wherein gravity causes the unbalanced arm to pivot clockwise until it engages stop pin 50. In FIG. 1A, it will be seen that detector arms 44a and 440 V have been forced in the counterclockwise direction by the presence of a workpiece.

For the purpose of illustration and description, this device has been assumed to have only four holding stations. As many additional units could be added as desired, it being understood that no detector arm or lift finger is needed to correspond to the uppermost. holding station (here shown as 34d). By other means not forming part of this invention, workpieces are conveyed to the uppermost rest arm and removed from the lowermost rest arm.

Mounted on the inner wall of frame is a lift finger retracting pin 52 (FIGS. 1A and 5) which comprises a spring loaded element which is biased to engage cam 54 mounted on lift finger 16c. Cam 54, preferably mounted on the uppermost lift finger, is shaped so that upon upward motion of lift finger 16c past spring loaded pin 52, lift finger is cammed clockwise to its inoperative position, causing the other lift fingers to follow by means of trip arms 28. Downward movement of cam 54 past spring loaded pin 52 only causes the pin to be depressed against its spring bias.

Referring to FIGS. 2A and 2B, and 3 in particular, there is illustrated a rest arm control bar 56 which is supported for vertical reciprocation by frame 10 (the support being unillustrated for clarity). Control bar 56 is provided with a plurality of notches 58 which function to control the position of rest arms 34 through the interaction of rest arm connecting bars 38 with the sides of notches 58. The motion of control bar 56 is controlled by control bar cam 60 on transfer bar 12, which causes pivotal movement of control bar link 62 pivotally mounted on stationary pivot pin 64 in response to its engagement with follower 66. Also functioning to control the position of each rest arm 34- is a rest arm stop 68 forming a portion of frame 10. Since transfer bar guide column 14 must be perforated to allow for passage and movement of connecting bars 38, the upper rim of each such passage may form the stops 68.

OPERATION Before describing the operation in detail, a few general operating principles of the mechanism will be described.

First, movement of any lift finger 16 to its inoperative position (that is, clockwise pivotal movement as viewed in FIG. 2A, for example) causes all lower lift fingers to similarly assume the inoperative position. This occurs because of the interaction of the adjacent trip arms 28, whereby the clockwise movement of a lift finger 16 causes its associated trip arm to move downwardly, thereby abutting and similarly forcing downward the next adjacent lower trip arm segment. Since adjacent trip arm segments 28 are not capable of exerting a tension force upon each other, the downward motion of one segment has no effect on adjacent upper segments.

Secondly, by reason of the same trip arm mechanism, the movement of any lift finger 16 to its operative position (that is, counterclockwise pivotal movement) moves all upwardly located lift fingers to their respective operative positions. As will be appreciated more fully upon a complete operation of the device, a solid or unsegmented trip arm would cause a workpiece to be delivered to an already occupied holding station.

Describing now the sequence of a typical cycle of the transfer bar 12, the initial position is as illustrated in FIG. 1A, wherein the transfer bar is at the bottom of its stroke. For the purpose of explanation, the lowermost station is shown as occupied by a workpiece 42a, as is the third work station from the bottom, which is occupied by workpiece 426. In between, there is an empty work station, as shown by the unoccupied rest arm 3412. Thus a single cycle of the transfer bar should be effective to transport workpiece 420 down to fill the empty station at 34b.

In the position of FIG. 1A, it Will be seen that all rest arms are in their operative position, since the rest arm connecting bars 38 are each supported by rest arm con trol bar 56 (FIG. 2A), which is still in its upper position. The weight of a workpiece on a rest arm causes connecting bar 38 to lift off notch 58 of control bar 56 and engage stop 68, as shown at 34c in FIG. 2A. Similarly, all lift fingers 16 are in their operative positions.

Detector arms 44a and 440 have each been cammed downwardly by the presence of the corresponding workpiece, while detector arm 44b has been allowed to pivot clockwise about its pivot pin 46 until its upper edge engages stop pin 50. This clockwise pivotal movement of detector arm 44b is caused by gravity and the shape of each arm, due to the excess weight on the right hand side of the point of pivotal support.

As transfer bar 12 starts its upward movement from its lowermost position (illustrated in FIG. 1A), the lift finger retracting cam 54 mounted on lift finger 16c comes into engagement with the lift finger retracting pin 52 secured to frame (FIG. 5). Continued upward movement of transfer bar 12 causes lift finger 160 to be cammed clockwise to its inoperative position. By reason of the trip arms 28, all downwardly located lift fingers 16 are similarly forced into their inoperative position. This step is necessary so that the lift fingers will be retracted as they pass their respective holding station at the beginning of their upward stroke. Otherwise, a workpiece would be lifted and returned to its orignal position.

As transfer bar 12 continues to move upwardly, the lift finger cam pin on detector arm 44!) is engaged by follower plate 26 on lift finger 16b, as illustrated in FIG. 1B. There, lift finger 1611 can be seen to be moving counterclockwise toward its operative position. The corresponding lift finger cam pins 48 on detector arms 44a and 440 do not engage the follower plate on lift fingers 16a and 166, respectively, because these pins are held out of the path of the corresponding follower plates by the presence of a workpiece at these stations. Through the interaction of trip arms 23, the counterclockwise camming of lift finger 16b similarly causes lift finger to be moved to its operative position. The position of the mechanism illustrated in FIG. 1B corresponds with that shown in FIG. 2A, wherein the action of trip arms 28 can be seen.

FIG. 2A also illustrates that any further upward movement of transfer bar 12 would cause rest arm control bar cam 60 to pass out of engagement with follower 66. When that occurs, rest arm control bar 56 drops to its lower position, as is illustrated in FIG. 2B.

In FIG. 1C, the transfer bar has continued its upward movement until lift finger 16b has just lifted workpiece 42c off of rest arm 340. As can be seen in FIG. 1C and corresponding FIG. 2B, rest arm control bar 56 has moved to its lower position, thus permitting unoccupied rest arms 34b and 34d to pivot to their inoperative positions, and allowing rest arm 340 to begin to pivot to that position. Rest arm 34c has not yet completed its movement in these illustrations, since it is still in partial engagement with lift finger-supported workpiece 42c.

Transfer bar 12 will continue to move up slightly beyond the position shown in FIGS. 10 and 2B, and then will commence its downward movement. Since unoccupied rest arms 34b and 34d are in their inoperative positions, and since detector arm 440 can pivot counterclockwise out of the path of downwardly moving workpiece 42c, there are no obstructions. It continues to move downwardly until its reaches the position of FIG. 1D, which is just before the completion of the downward stroke. Here, the workpiece 420 is about to be deposited upon rest arm 34b.

Further downward movement of transfer bar 12 brings cam 60 into engagement with follower 66, thus lifting rest arm control bar 56 to its upper position (FIG. 2A), and positively returning all rest arms to their operative positions.

Thus, worthpiece 420 has been moved downwardly from station 340 to fill the previously empty station 34b. Had a workpiece been present at station 34d, it would have similarly and simultaneously been moved downwardly by lift finger 160 on a single stroke cycle of transfer bar 12. If all holding stations are occupied, transfer bar 12 continues to reciprocate, but nothing happens, since lift finger cam pins 48 do not cause the lift fingers to leave their inoperative positions.

One of the primary advantages of the operation provided by this unique mechanism is that all workpieces located rearwardly of an empty work station will be moved forward simultaneously by a single cycle of transfer bar 12.

This invention may be further developed within the scope of the following claims. Accordingly, the above specification is to be interpreted as illustrative of only a single operative embodiment of this invention, rather than in a strictly limited sense.

I now claim:

1. An accumulating transfer mechanism for downwardly conveying workpieces in discrete unidirectional steps in a substantially vertical path comprising:

a frame;

a vertically oriented transfer bar guidably mounted on said frame for vertical reciprocation relative thereto, and having a stroke slightly longer than the length of incremental travel of the workpiece;

a power source for causing said transfer bar to reciprocate;

a plurality of vertically spaced rest fingers pivotally mounted on said frame at intervals equal to the length of incremental travel of the workpieces, said rest fingers functioning as workpiece holding stations when positioned in an operative position in the path of workpiece travel, and lying out of the path of workpiece travel when in an inoperative position;

rest finger positioning means movably mounted on said frame for selectively causing said rest fingers to be placed in their operative position in the path of workpiece travel, or in their inoperative position out of such workpiece path;

a plurality of vertically spaced lift fingers pivotally mounted on said transfer bar for downward transporting workpieces from one rest finger holding station to the next adjacent lower holding station, and being selectively movable between an inoperative workpiece-bypassing position and an operative position in the path of workpiece travel;

lift finger connecting links mounted on said lift fingers for selectively linking together selected ones of said lift fingers for pivotal movement in unison, by which the movement of a given lift finger to its operative position causes said connecting links to similarly position all other upwardly located lift fingers, and the movement of a given lift finger to its inoperative position causes said connecting links to similarly position all other downwardly located lift fingers;

lift finger retracting means secured to said frame for engaging and camming said lift fingers to their inoperative positions upon the commencement of the upward stroke of said transfer bar;

a plurality of vertically spaced workpiece detector arms pivotally mounted on said frame, one at each workpiece holding station except the uppermost holding station, each detector arm assuming a position responsive to the presence or absence of a workpiece at its associated holding station, each detector arm when positioned in response to an empty holding station having means to cam the next adjacent lower lift finger to its operative position as it passes said detector arm on the upward stroke of said transfer bar.

2. The transfer mechanism of claim 1 wherein said rest finger positioning means is actuated in response to the position of said transfer bar to normally maintain said rest fingers in their operative positions, but to momentarily permit all unoccupied rest fingers to move to their inoperative positions from the time near the top of the upward stroke of said transfer bar when the lift fingers initially engage a workpiece to be transported downwardly to the time when said workpieces have been transported downwardly beyond their respective previous holding station position.

References Cited UNITED STATES PATENTS 3,190,488 6/1965 Holstein 22l-75 RICHARD E. AEGERTER, Primary Examiner US. Cl. X.R. 22l-75

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