Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
1999-04-06
2001-02-27
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
Separators
C271S003050, C271S004010, C271S004080, C271S010010, C271S042000
Reexamination Certificate
active
06193229
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to sheet material handling systems, and more particularly to devices for separating signatures.
2. Background Art
The binding and printing industries often rely on high-speed sheet material handling systems for printing, collating signatures and binding the collated signatures. A typical system includes a stack of signatures, a separator, a sucker arm, a feed drum and a conveyer for collating signatures. The separator separates signatures from a stack of signatures. The sucker arm draws the separated signature towards the feed drum. The feed drum rotates, griping the separated signature and delivering it to the conveyer. The conveyer transports the signature for collation, binding and other operations, for example. Typically, a common drive mechanism drives the separator, sucker arm, feed drum and the conveyer.
Throughput depends on how closely together the signatures are spaced, and on how fast the signatures are moved. Accordingly, throughput may be optimized by spacing signatures as closely together as possible and by maximizing system speed.
Rotational speed of the separator disk is of fundamental importance to handling system performance. The faster the separator disk can rotate from the position where it enters the stack of signatures to a second position where a signature is separated, the better system throughput can be.
In an apparent attempt to overcome limitations to higher throughput rates, a sheet material handling apparatus is disclosed in U.S. Pat. No. 5,531,433 to Hawkes et al. This disclosure is incorporated herein by reference. Hawkes et al. recognize the problem of minimizing velocity mismatch between the conveyer and the feed drum. The proposed solution is to provide a rotatable ring member around a feed drum. The ring member rotates to have a velocity close to that of the conveyer. Hawkes et al. address the velocity mismatch between the conveyer and the feed drum.
Assuming that the Hawkes et al. feed drum delivers signatures faster and more reliably than a standard feed drum, the separator for the Hawkes et al. apparatus must operate fast enough to keep the feed drum properly supplied with signatures. Simply speeding up an existing separator may not be effective because the common drive mechanism may require the feed drum and the sucker bar to operate at a rate proportional to the separator speed. Accordingly, a faster way of delivering signatures to the feed drum is desired.
In typical handling systems having an array of feeders, the common drive mechanism includes a mechanically driven shaft and the array of separators and the feed drums are chain driven by the shaft to rotate at a rate proportional to the rate of shaft rotation. Such shaft driven systems are not always easily adjustable. Fine tuning the operation of the separator, feed drum and sucker arm takes time and effort. As a result, optimizing throughput is not a simple task, particularly when the handling system feeders feed signatures of various sizes.
U.S. Pat. No. 5,499,803 to Farr discloses a shaft driven material handling system having an array of feeders, the disclosure of which is incorporated herein by reference. The Farr system is broken into subsystems having discrete signature feeders. Each sub system operates on a separate drive shaft. Accordingly, each subsystem can be optimized independently to maximize throughput rates. Farr, however, fails to disclose a way of individually optimizing the feeders. Accordingly, what is desired is an improved way of feeding signatures that optimize handling system throughput.
SUMMARY OF THE INVENTION
The present invention includes a feeder for delivering stacked signatures to a conveyer. The feeder has a rotatable feed drum, a rotatable separator disk, a variable speed servomotor and a servo control system.
The separator disk has a blade with a leading edge and a trailing edge. The servomotor mechanically couples with the separator disk to rotate the blade at a variable speed from a first position where the leading edge contacts the stacked signatures, to a second position, where the blade exits the stacked signatures, to a third position. The separator disk separates a signature, forcing the separated signature towards the feed drum. Separation occurs at a point while the separator disk rotates between the first position and the second position.
The feed drum has a periphery with at least one gripper. The feed drum rotates the gripper into a gripping position with respect to the separated signature, grips the separated signature and delivers it to the conveyer.
After the separator disk exits from the stacked signatures, the blade slows to the third position. The blade reaches a minimum velocity in the third position. Slowing the disk provides time for the feed drum to deliver the separated signature to the conveyer.
The servo control system couples with the servomotor to regulate servomotor speed and acceleration. The servo control system is programmable to assure that the separator disk blade moves between the first position and the second position as quickly as practical. The control system can be manually operable at the feeder, may be controlled from a desktop computer, or may be integrated into a network of control systems designed to optimize handling system throughput. It can be appreciated that the servo control system and servomotor can be integrated with new feeder designs, or be retrofit on existing feeders.
According to one aspect of the invention, the feeder includes a command signal generator and a comparator. The command signal generator couples to the feed drum and to the comparator for detecting feed drum position and communicating feed drum position to the comparator. The comparator couples with the servo control system to coordinate the separator disk rotation with the feed drum rotation so that the gripper enters the gripping position when the separator disk separates a signature from the stacked signatures.
The servo control system includes a servo amplifier coupled with the comparator. The comparator detects servomotor position error and communicates a signal reflective of the position error to the servo amplifier. The servo amplifier amplifies the position error signal and communicates the amplified signal to the servomotor to cause the servomotor to automatically rotate the separator disk to eliminate the position error.
According to one aspect of the invention, the feeder is part of a multi-feeder system, each servomotor includes an absolute encoder coupled with the comparator to deliver separator disk position information to the comparator. According to an alternate aspect of the invention, the servomotor includes an incremental encoder coupled with the comparator to deliver separator disk position information to the comparator.
The separator disk has a single blade and the servomotor rotates the separator disk in a single direction for separating signatures. In an alternate embodiment of the invention, the separator disk has two opposing blades and the servomotor is reversible to selectively rotate the separator disk in either of two directions.
The present invention employs a servo control system to gain several advantages over existing direct-drive type systems. One advantage is that the servomotor and separator disk can be readily inhibited by electronically deactivating the servomotor. Inhibiting the servomotor is desirable in situations where a single feeder in a multi-feeder system is required to skip feeding signatures for one or more system cycles. The servomotor may be inhibited manually or by pre-programming the feeder to inhibit the servomotor for a predetermined number of cycles at a particular time.
Another advantage is that servomotors are independently adjustable in position and speed. It is possible to adjust the relative position of a mis-aligned separator disk by shifting the position of the servomotor with respect to the stacked signatures while the feeder operates. This eliminates the necessity of turning the machine
Hall David F.
Prim Jonh E.
Beauchaine Mark J.
Fortin, Esq. Kevin H.
Walsh Donald P.
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