US3257109A - Regenerative system for alternating motion - Google Patents

Description

June 21, 1966 M. v. slNGH 3,257,109

REGENERATIVE SYSTEM FOR ALTERNATING MOTION v Filed Jan. 6, 1964 5 Sheets-Sheet l June 2l, 1966 M. v. SINGH REGENERATIVE SYSTEM FOR ALTERNATING MOTION 5 Sheets-Sheet 2 Filed Jan, 6, 1964 INVENTOR.

MAHENDRA VIR SINGH BY June 21, 1966 M. v. slNGH 3,257,109

REGENERATIVE SYSTEM FOR ALTERNATING MOTION Filed Jan. 6, i964 5 Sheets-Sheet 5 y Mahendra Vir Singh, Chicago, Ill., assignor to Miehle- Goss-Dexter, Incorporated, Chicago, lll., a corporation of Delaware Filed lan. 6, 1964, Ser. No. 335,740 9 Claims. (Cl. 271-51) The invention relates to alternating motion devices and to regenerative systems therefor, and has reference more particularly, to oscillating sheet infeed gripper mechanisms for printing presses havingy improved means for counterbalancing the gripper inertia torques.

The motion of an infeed gripper mechanism on a sheet fed press must be such that following front and side registration on the registering table, the sheet is gripped, accelerated to press speed as gently as possible, and transferred to the auxiliary transfer cylinder on impression cylinder grippers at press speed. If-an oscillating infeed gripper mechanism is employed, the said mechanism has to be brought to rest and returned to the register table in such a way as to cause no interference with the driving means or with the sheet being printed by the press. At the registering table the oscillating infeed gripper mechanism must come to rest in time for receiving the next sheet.

Conventional drive mechanisms for oscillating the sheet infeed gripper mechanisms employ linkages or a combination of links and cams. Conjugate cams are conventionally used since they permit elastic preloading of the drive mechanism, thus minimizin-g backlash inthe mechanism and which reduces the positioning errors of the motion. Such cams also eliminate the need for a return spring but this fact is less significant than the ability to preload the mechanism in order to reduce backlash. However, even though conjugate cams may or may-not be used, the large forces and torques resulting from the accelerations and decelerations of the oscillating infeed gripper mechanism can be the source of shock and vibrations in the press with resultant disturbance of the printing process.

In view of the foregoing a basic objective, of the invention is to provide improved mechanism for reducing disturbing forces and torques in alternating motion devices, particularly oscillating infeed gripper mechanism for printing presses, Whileretaining all the desirable features of the conjugate cam drive means for such devices.

The cyclic motion of theoscillating sheet infeed gripper mechanism is somewhat similar to the natural movement of an oscillating system consisting of resilient spring means and an oscillating mass. Such cyclic motion is referred to as simple harmonic motion and the same corresponds to that motion which such mass spring system would execute in the absence of external forces and friction. The desired oscillating motion of the infeedV -gripper mechanism deviates from simple harmonic motion in several irnportant respects. In the first place the required timing sequence of the press is such that the infeed gripper must remain at rest at the registering table for a finite period to permit the gripper elements thereof to accurately and positively engage a registered sheet. Also, at the opposite extremity of the gripper motion it is desirable for the same to remain at rest momentarily to permit the transferred sheet to be withdrawn before the infeed gripper returns to the registering table. Furthermore, the velocity, acceleration and rate of change of acceleration characteristics for simple harmonic motion are not necessarily such as to move the sheet with minimum force and disturbance. Also, at transfer 4to the impression cylinder it is necessary that the velocity of the infeed grippers remain constant for a nite length of time to permit smooth transfer ofthe sheets from the infeed grippers to the impression cylinder grippers. Moreover, the simple harmonic motion pro- 3,Z57,lii9 Patented .lune 21,1966

duced by a particular spring and mass has one, and only one, characteristic frequency, whereas the movement of the infeed grippers must be in time with the press at all operating speeds up to maximum press speed.

Another object of the invention resides broadly in the provision of regenerative means for oscillating motion devices, and more specifically lin the provision of sheet infeed gripper mechanism for a printing press which will employ a conjugate cam system in combination with a torsion bar for storing energy during the decelerating periods and for returning the stored energy during the accelerating periods.

Thus the basic improvement contemplated by the invention includes regenerative means in the form of a torsion bar located centrally of a hollow supporting shaft. Since the motion required for proper infeed mechanism operation is governed by the conjugate cam profile and which is similar though not identical to the natural motion produced by the torsion bar, the net forces and torques produced by the cam and drive linkage are substantially below those which would otherwise occur.

The primary factors relating to the difference between the natural motion and the motion actually required are accounted for as follows:

(a) The dwell period at the register table to permit the infeed grippers to accurately and positively engage a .registered sheet;

(b) The deviation of the characteristics from natural harmonic motion to obtain the desired motion of the sheets; r-

(c) The consant speed period to effect transfer of the sheet to the impression cylinder grippers;

(d) The dwell period 'at the end of the infeed gripper stroke to permit the transferred sheet to be withdrawn :before the grippers are returned to the register table;

(e) Variations in the oper-ating speed of the press.

The net resultant torques due to the above deviations from natural harmonic motions are significantly reduced, if not completely nullied by providing a regenerative torsion bar system.

An addi-tional object of the invention is to provide torsion A'bar mechanism such as described which will incorporate adjustable means for varying the effective length of the bar so that the bar can be tuned for minimum net forces at any Aparticular press speed.

With these and various other objects in view the invention may consist of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended thereto;

In the `drawings which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- FIGURE 1 is a schema-tic view showing oscillating infeed gripper mechanism applied to a printing press and illustrating the use of conjugate cams for oscillating said gripper mechanism;

FIGURE 2 is a Vertical sectional view showing a practical embodiment of the improved infeed gripper mechanism of the invention applied to the impression cylinder of a printing press and additionally showing conjuga-te cams for operating the said gripper mechanism;

FIGURE 3 'is a fragmentary elevational view with parts being shown in section for illustrating the construction and mounting in the sideframes Aof a press of oscillating infeed gripper mechanism with torsion bar, all as contemplated by the present invention;

FIGURE 4 is an end elevational View taken substantially along line 4-4 of FIGURE 3 and looking in the direction of the arrows; and

FIGURE 5 is a diagram showing actual values'of the oscillating infeed gripper mechanism inertia torque Iplotted against instantaneous values of the torsion rod torque.

Although the vregenerative system as contemplated by the invention can be employed in alternating motion devices of various types, the embodiment selected for illustration comprises oscillating sheet infeed gripper mechanism for sheet fed printing presses having conjugate cams for operating the same and having regenerative means in the form of a torsion bar. As shown in FIGURE 1 the numeral indicates an impression cylinder of a printing press. A plate cylinder 11, a blanket cylinder 12, and a transfer cylinder `13 are operatively associated with the impression cylinder in the conventional manner. The sheets to be printed are supported by the registering table 14 and the oscillating sheet infeed mechanism 15 is operative for transferring a sheet from the table to the gripper structure 16 carried by the impression cylinder. The sheet -so transferred is printed as it passes between the impression and blanket cylinders, and following said printing operation the sheet is delivered to the gripper device 17 carried by the transfer cylinder. The conjugate cams 18 and 20 are rotated in timed relation with the impression cylinders and the rollers 21 and 22 contact the cams respectively to oscillate the arms 23 and 24 of the bell crank 25 having a pivot support at 26. By means of the link 27 and the lever 28 the oscillating movement of the bell crank 25 is imparted to the infeed gripper mechanism 15.

FIGURE 2 shows one embodiment of practical operating structure for oscillating the gripper mechanism of a printing press .by means of conjugate cams such as schematically illustrated in FIGURE 1. The impression cylinder 10 has associated Itherewith the gear 30 which meshes with the gear 31 on the shaft 32 to which the conjugate cams 18 and 2f) are xed. Thus the cams and the impression cylinder are -rotated in timed relation and it follows that the gripper structure 15 will also have movement in timed relation with the impression cylinder. It will be observed that roller 21 has Contact with cam 18 and that roller 22 has contact with cam 20. The bell crank 25 is oscillated on its pivot 26 in a manner as determined by the profiles of said cams. From the bell crank the oscillating motion thereof is transmitted by the link 27 to the lever 28 and by said leverto the hollow supporting shaft 34 of the infeed gripper assembly. The construction and mode of operation of said hollow shaft will now be described in connection with FIGURE 3.

The-said hollow shaft 34 is Iprovided with end members 35 and 36 which in turn provide the extensions 37 for journalling the gripper bar 38. Said bar carries a plurality of gripper fingers which are adapted to coact with the pads 41 for gripping and retaining the sheets transferred by the mechanism to the impression cylinder. A hub portion 42 projects from end member 35 and said hub member is journalled in a conventional manner in the side frame 43 of the press as by the ball bearing 44. The said bearing structure 44 has location in the bore 45 formed in this side frame. The end member 36 also provides a hub portion such as 46 which extends through the bore 47 in the side frame 48 so as to project beyond the side frame on the right hand side thereof. The roller bearing 50 journals the hub portion 46, the outer ring of the said bearing being held in place by a shoulder within bore 47 and by the retainer 51. The collar 52, shown in section in FIGURE 3, forms the terminal end of the lever 2Sand by mounting the collar on the hub portion 46, the lever can be iixedly secured to the hollow supporting shaft 34. This is accomplished by employing a block 53 which is ixedly secured `by the bolt 54 to the hub portion 46 and which has interfitting relation with the collar 52. The -collar in turn contacts the inner ring of the bearing structure 50 and since said inner ring is backed by the shoulder 55 forming part of the hub portion 46, the block 53, collar 52, and inner bearing ring are all fixedly secured to the hub portion 46 of the supporting shaft 34.

The invention employs regenerative means in the form of a torsion bar 56 which extends longitudinally of the hollow shafts 34, being supported by the shaft for independent rotation by the intermediate partition 57 which provides the `bearing 58. The right hand end of the torsion bar extends through the hub portion 46 and through the lblock 53, and said end is secured to the block by the spline connection 69. Accordingly, this right hand end of the torsion ibar is fixed to the hollow shaft 34, since it is splined to the block 53 which is in turn iixedly secured to the hub portion 46 of the shaft. The left hand end of the torsion `bar extends through the hub portion 42 which provides the bearing 61 for supporting said end for rotating movement independently of the hub portion. The extending end of the torsion bar beyond the bearing 61 is provided with the splined formation 62 which interfits with a similar lformation located centrally of the longitudinally adjustable anchoring nut 63. The main body portion of the anchoring nut has a splined formation 64 formed on its peripheral surface for interfitting with a similar formation 65 on the interior surface of the bore 45, and thus the anchoring nut is free for movement in a longitudinal direction but is effectively prevented from rotating with respect to the frame of the press. The hub portion of the anchoring nut 63 is provided with the peripheral threads 66 and this threaded portion extends through the center of the gear wheel 67 which has internal threads that mesh with the threads 66.

A cover plate 68 is xed to the frame 43 by the securing bolts 70. Said cover plate substantially encloses the gear wheel 67 so as to confine the gear wheel between the cover plate and the side frame of the press, although permitting rotation of the gear wheel on the threaded portion 66 of the anchoring nut 63. The flanges 71, FIGURE 4, comprise an integral part of the cover plate 68 andsaid anges journal the shaft 72 on which is fixed the worm gear 73, located lbetween the anges and having meshing relation with the gear wheel 67. The extending left hand end of the shaft 72 is squared at 74 for receiving a tool or the like for manually rotating the worm gear 73 to in turn 4rotate the gear wheel 67. It will be understood from the foregoing that by adjusting the position of the anchoring nut 63 axially within bore 45 the effective length of the torsion bar 56 can be varied.

In operation of the gripper mechanism as described, the shaft 34, the gripper bar 38 and the gripper fingers 4and pads 4d and 41 are oscillated by the conjugate cams 18 and 20 from a position A adjacent the registering table 14 as shown in dotted lines in FIGURE 2 to a transfer position shown in full llines in said figure, at which time the sheet is transferred to the impression cylinder. The oscillating motion of the gripper structure continues for some distance beyond the transfer position until position B is reached, whereupon the gripper structure is brought to rest and reverse oscillating motion takes place for returning the same to the registering table. The profiles of the conjugate cams are designed to accelerate the gripper structure as it moves from position A to adjacent the transfer position. For a short distance in advance of and following the tranfer point for the sheet, the speed of the gripper structure is constant and precisely equal to the peripheral speed of the impression cylinder 10. This is required in order to effect proper transfer of the sheet by the gripper structure to the impression cylinder. Following transfer, the gripper motion gradually decelerates until a position of rest is reached at B comprising the other extremity of the gripper motion. Gn the return movement the gripper structure will again accelerate from position B until the intermediate transfer point is reached, whereupon the structure is decelerated until it cornes to rest in contact with the registering table 14 at position A.

The oscillating motion of the gripper structure with the alternating accelerating and decelerating periods have been the source of shock and vibrations in the press with resulting disturbance in the printing process. The affect of `the instantaneous changes in-inertia torque which are imposed on the drive system by the infeed gripper mechanism during a normal cycle of operation of a printing on the drive mechanism which is transmitted through the drive gears 31-30 to the impression cylinder. This, in turn, produces a slight slip at the nip between the impression cylinder and the blanket cylinder 12 which produces a series of streaks on the sheet S in the area which is receiving an impression from the blanket cylinder at the point X.

The instantaneous shock also is transmitted to the blanket cylinder causing the latter to slip slightly relative to the plate cylinder 11 with the further result that the ink impression being applied to the surface of the -blanket cylinder at point Y will also be distorted and will become evident by a second set of streaks which will appear on the sheet S at about the point Z.

A similar set of conditions will prevail upon the deceleration of the infeed gripper mechanism at the end of the feed stroke and also upon the acceleration and deceleration of the mechanism during the return stroke.

The disturbing forces and torques incident to the oscillating motion of the gripper structure are substantially reduced if not entirely eliminated, however, bythe torsion bar 56, which is `iixed by the splined connection 60 at one end` to the hollow shaftl 34, and is anchored at its opposite end by a splined connection to the side frame of the press through the adjustable anchoring nut 63. On the decelerating portions of the oscillating motion as imparted to the gripper structure the torsion rod 56 will 'be twisted in a manner to store up energy in the rod. The twisting action is a maximum at the spline connection 60 which secures the torsion rod to the hollow shaft and progressively decreases in extent to the opposite end which is anchored in the press frame by the adjustable anchoring nut 63. On the following accelerating portion of the oscillating motion the stored up energy in the torsion rod 56 is released to assist the accelerating action of the gripper motion. The release of the stored up ene-rgy in the torsion rod continues until the transfer point is reached, whereupon the cycle is repeated on the following decelerating portion, since the torsion rod is against twisted as described with a maximum twisting action -being reached at respective terminal ends A and B of the oscillating motion.

When a torsion rod is employed in accordance with the present invention the net forces and torquesl produced by the cam and drive linkage and by the resulting oscillating *motion of the gripper structure are reduced to a minimum. T-his can best be understood by reference to FIGURE 5 wherein instantaneous values of infeed gripper inertia torque and torsion rod torque have been plotted against each other to show the counterbalancing action of the latter. The'line 75 represents the .inertia values of infeed gripper torque for decelerating and accelerating periods, Whereas line 76 represents the values of the torsion rod torque for the same periods. The infeed gripper inertia torque is shown as decreasing in value during the accelerating period, namely from the top left hand position to approximately twelve degrees in. advance of the transfer point T. During this period and for approximately twelve -degrees beyond the point T, the gripper structure moves at a constant speed equal l to the peripheral speed of the impression cylinder to effect proper transfer of the sheet. Accordingly the inertia torque is zero `for said period. The lower path of line 75 indicates the inertia torque for the decelerating motion of the infeed gripper structure and which is shown as increasing in value until the lower right hand position is reached. It will be observed that at each end of the oscillating motion when the infeed gripper torque is a maximum, the torsion rod torque is also a maximum and is directly opposed thereto. On both sides of the point T the torque of the torsion rod will be greater than the inertia torque of the gripper structure, since the latter is moving at a constant speed. T-he difference is indicated in the diagram of FIGURE 5.

While the invention has been disclosed herein as incorporating adjustable means for varying the spring characteristics of the torsion bar so as to provide minimum net torques at all operating speeds, it will be understood that such adjustability may not be essential under all circumstances. For example, if a machine is adapted to operate at a fixed `speed or within a narrow range of variation, a torsion bar having fixed characteristics will function with complete effectiveness. Moreover, it is a known fact that most printing presses have an optimum speed at which they produce the highest quality products and they are seldom operated at speeds much above or below the optimum. Consequently a torsion bar which is tuned to provide minimum net torques at the optimum speed will be adequate since it will still serve to maintain the torque values at relatively low levels during those periods when a press might be operated at other than its optimum speed. v

IIt should also be understood that while manually adjustable means have been disclosed for adjusting the effective length of the torsion bar this function also can be accomplished automatically by mechanism associated with the press drive so that the characteristics of the torsion ibar will be varied automatically and with direct relation to changes in press speed.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings as various other forms of the device will, of course, be apparent to those skilled in the art without-departing `from the spirit of the invention or thescope of the claims.

What is claimed is:

1. In a printing pres-s, in combination, oscillatable sheet transfer mechanism for said press including a shaft journalled for oscillating movement in the side frames of the press, drive means for producing oscillating motion of said shaft to cause the same to move in a manner which approximates simple harmonic motion, a torsion member, means connecting one end of the torsion member to the adjacent end of said shaft, and other means connecting to the opposite end of the torsion member to a side frame of the press whereby energy is stored in the Vtorsion member during the decelerating periods of said motion and is released to the shaft during the accelerating periods of said motion.

2. A printing press as set forth in claim 1 wherein said other means includes an adjustable member for varying the effective length of the torsion -member to compensate for variations of inertia torque resulting from changes in operating speed.

3. In an oscillating motion device, in combination, a mass adapted to have oscillating motion between two positions of rest spaced a distance from each other, cam

l means Ifor producing the oscillating motion of the mass with said mass and being so constructed and arranged that energy is stored in the torsion rod during the devariations of inertia torque resulting from changes in' operating speed. t

5. An oscillating motion device as defined by claim 3, wherein the cam means Ifor producing the oscillating motion of the mass comprises conjugate cams.

6.111 a printing press, in combination, oscillatable gripper structure for the printing press, drive means for producing oscillating motion of the gripper structure to cause the same to move in a manner which approximates simple harmonic motion, and regenerative means having associated relation with said gripper structure and being 4so constructed :and arranged that energy is stored in said means during the decelerating periods of said motion and is released to the gripper structure during the accelerating period-s.

7. In a printing press, in combination, oscillatable gripper structure for said press including a gripper shaft journalled for oscillating movement in the side frames of the press, conjugate cam means for producing oscillating motion of the gripper shaft to cause the same t-o move in a manner `which approximates simple harmonic motion, a torsion rod extending longitudinally and substantially axially of the gripper shaft, means fixing one end of the torsion rod to the adjacent end of the gripper shaft, and other means fixing the opposite end of the torsion rod to a side frame of the press.

8. In a printing press as defined by claim 7, wherein the other means for fixing the opposite end of the torsion rod to a side frame of the press includes an adjustable nut having a splined connection with said torsion rod and with the side frame, whereby the nut is held against rotation but is movable in an axial direction to vary the effective length of the torsion rod.

9. In a printing press, in combination with spaced sidek frames of oscillatable gripper structure for said press including a hollow supporting shaft having hub portions at respective ends, bearing structure provided Iby the side frames respectively for journalling the said hub portions, conjugate cams for producing oscillating motion of the supporting shaft to cause the same to move in a manner which approximates simple harmonic motion, a torsion -rod extending longitudinally and substantially axially of the supporting shaft, means fixing one end of the torsion rod to the hub portion at said end, the opposite end of said torsion rod extending through the other hub portion and being journalled thereby for independent rotative movements, an anchoring nut located in a bore in one side frame of the press in axial alignment with said other hub portion, said anchoring nut having a spline connection `with the interior surface of said bore whereby the nut is held against rotation but is movable within the bore in an axial direction, said torsion rod having an end projecting beyond the other hub portion, means providing a spline connection between said projecting end of the torsion rod and the anchoring nut, and manually operable means `for electing axial movement of the anchoring nut whereby to vary the effective length of the torsion rod.

References Cited by the Examiner UNITED STATES PATENTS 9/196'1 Great Britain.

M. HENSON WOOD, JR., Primary Examiner. ALLEN N. KNOWLES, Assistant Examiner.

Claims (1)

1. 6. IN A PRINTING PRESS, IN COMBINATION, OSCILLATABLE GRIPPER STRUCTURE FOR THE PRINTING PRESS, DRIVE MEANS FOR PRODUCING OSCILLATING MOTION OF THE GRIPPER STRUCTURE TO CAUSE THE SAME TO MOVE IN A MANNER WHICH APPROXIMATES SIMPLE HARMONIC MOTION, AND REGENERATION MEANS HAVING ASSOCIATED RELATION WITH SAID GRIPPER STRUCTURE AND BEING SO CONSTRUCTED AND ARRANGED THAT ENERGY IS STORED IN SAID MEANS DURING THE DECELERATING PERIODS OF SAID MOTION AND IS RELEASED TO THE GRIPPER STRUCTURE DURING THE ACCELERATING PERIODS.

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