US3114313A

US3114313A - On-off impression mechanism for two cylinder printing presses

Info

Publication number: US3114313A
Application number: US60079A
Authority: US
Inventors: Udall Humfrey Nicholas
Original assignee: Linotype and Machinery Ltd
Current assignee: Linotype and Machinery Ltd
Priority date: 1959-10-06
Filing date: 1960-10-03
Publication date: 1963-12-17
Anticipated expiration: 1980-12-17

Description

Dec. 17, 1963 H. N. UDALL ON-OFF IMPRESSION MECHANISM FOR TWO CYLINDER PRINTING PRESSES 6 Sheets-Sheet 1 Filed Oct. 3, 1960 mvsu-rok N t A-r-rokuevs Dec. 17, 1963 H. N. UDALL 3,114,313

ON-0FF IMPRESSION MECHANISM FOR TWO CYLINDER PRINTING PRESSES Filed Oct. 5, 1960 6 Sheets-Sheet 3 INVENTOR WWW/Mm W Aw-r aNev Dec. 17, 1963 DALL 3,114,313

H. N. u ON-OFF IMPRESSION MECHANISM FOR TWO CYLINDER PRINTING PRESSES Filed Oct. 5, 1960 6 Sheets-Sheet 4 lNvEN-roR X/MWLQ Y Dec. 17, 1963 H. N. UDALL ON-OFF IMPRESSION MECHANISM FOR TWO CYLINDER PRINTING PRESSES Filed Oct. 3, 1960 6 Sheets-Sheet 5 122 127 I24 I28 I23 I25 F/GJO.

INVENTOR 7 X/MW MW JW ATTORNEYS H. N. UDALL ON-OFF IMPRESSION MECHANISM FOR TWO Dec. 17, 1963 CYLINDER PRINTING PRESSES Filed 001:. 5, 1960 6 Sheets-Sheet 6 lNvENToR KIM W w M, .Nw m ML on n W M u A 3 on Hmo 5 q m o L I Hwo Ni H8 2, n H/ a a www Em mm N Q -Q a N9 a. 5 I RQL 26x6 22935? United States Patent 3,114,313 (IN-OFF IMPRESSION MECHANISM FOR 'I'Wt) CYLINDER PRENTING PRESES I-Iumfrey Nicholas Udall, Timperley, England, assignor to Linotype and Machinery Limited, London, England, a British company v Filed Oct. 3, 1960, Ser. No. 60,079 A Claims priority, application Great Britain Get. 6, 1959 23 Claims. (Cl. 101192) The present invention relates to printing presses, and means for ensuring that the impression cylinder, or cylinders in the instance of two colour or perfector presses, will assume a correct on-oii impression cycle subsequent to, for example, the running of the press with the impression cylinder or cylinders in the off impression condition.

In its simplest form the invention is applicable to single impression cylinder printing presses, but examples of the present invention are also applicable to printing presses of the two impression cylinder type such as two colour printing presses or perfector printing presses in which each impression cylinder will contact a separate form only during a printing period of the printing press cycle.

in two impression cylinder printing presses the impression cylinders perform cyclic alternate on-ofr' 14- pression movements during printing operations. The impression cylinders of a perfector printing press have a half cycle difference between impressions, but in the instance of a two colour printing press the impression cylinders operate in a substantially on-otf impression cycle together.

In printing presses incorporating the present invention the on-impression movement of the impression cylinder 0r cylinders is preferably etlected hydraulically, the control of the system being effected electro-mechanically. The same control system can, however, be applied to a mechanical pull down arrangement for the impression cylinder or cylinders.

In two impression cylinder printing presses, when hot impression cylinders have been raised to the oil-impression position, and the printing press is run for any reason, it is essential that on the completion of the circuit controlling the on-off impression mechanism, the on impression movement of an impression cylinder will not take place until its correct time in a complete printing cycle which is about to commence. With two impression cylinders it is further essential that the correct working relationship with regards to impression movements shall be established immediately. This means that the second impression cylinder must be held oil impression until the first impression cylinder has completed its first on impression cycle.

The control means suitable for a one impression cylinder printing press can be utilised for the control of one of the impression cylinders of a two impression cylinder printing press, and the control for the other impression cylinder of the printing press is ellected by a duplication of the control means with certain modifications and additions.

According to the present invention there is provided a control system for the impression mechanism of the impression cylinder of a printing press comprising means operated in synchronism with the printing press drive for holding out the on impression stroke of the impression mechanism until the correct time for such an on impression stroke in a complete printing cycle of the printing press obtains.

Also, according to the present invention, there is provided a control system for the impression mechanism of the impression cylinder of a printing press comprising a first means controlling the cyclic on-ofi impression move ments of the impression mechanism and second means 3,114,313 Patented Dec. 17, 1963 holding the first means in an oil impression condition until the correct timing sequence for a complete printing cycle is obtained.

Likewise according to the present invention there is provided a control system for the impression mechanism of the impression cylinder of a printing press provided with a cam driven in synchronism with the printing press drive, a valve controlling the impression mechanism, which valve has a spindle normally urged to the on impression position, a locking mechanism for retaining the valve spindle in the off impression position and means to release the lock, the cam during part of its movement thrusting the valve spindle to an oil impression position and allowing the spindle to return to the on impression position during the remainder of the cam movement, the latch being held out during printing operations to allow of cyclic movement of the valve spindle, the dropping of the latch becoming effective to lock the valve spindle in the off impression position when the valve spindle is thrust into that position by the cam, the valve spindle being latched thus even on actuation of the latch lifiing means until the oil impression portion of the cam is in the operative position relative to the valve spindle, whence the latch will lift, the arrangement being such that the valve spindle will be locked in the off impression position until the correct timiu sequence for a complete printing cycle obtains.

The control system is preferably electrically operated and is coordinated with means synchronized with a printing cycle for the printing press, which means cooperate With impression mechanism effecting impression cylinder pull down, the electrical control system and its associated means "operating in such manner that when an impression circuit is closed the impression mechanism of the impression cylinder cannot operate to bring the cycle into an on impression condition until the beginning of a complete printing cycle. When the control system im applied to a two impression cylinder printing press the impression mechanism of the second impression cylinde-r Will be restrained from operating until such time as the correct cyclic relationship of 01 -on impression between the two impression cylinders can be established.

Examples of the control system, according to the present invention are shown in the accompanying drawings in which;

FIGURE 1 is a side elevation or" the mechanism for combining the movements of a solenoid and a cam cperated by the press to effect control of a valve,

FIGURE 2 is an end elevation of the same mechanism,

FIGURE 3 is a circuit diagram of the electrical devices involved,

FIGURES 4 to 6 are somewhat schematic details of control system elements, in different positions, for the control of the second impression cylinder of a two impression cylinder printing press,

FIGURE 7 is a detail of the means controlling the hydraulic system shown in FIGURE 10,

FIGURE 8 is a sectional detail taken on VII-VII FIGURE 7,

FIGURE 9 shows a modification of the control system elements shown in FIGURES 4 to 6,

FIGURE 10 shows a modified hydraulic pull down system for the impression cylinder and the means for controlling the hydraulic system, and,

FIGURE 11 is a diagram of the electrical circuit of the control system, for a two impression cylinder printing press. Both impression cylinder control circuits being shown.

Referring to the FIGURES 1 and 2, a cam It having a circular portion 11 and a circular portion I2 of greater diameter than portion 11, is rotated in synchronism with the printing press drive and is engaged by a cam follower 3 13 carried on an arm 14 pivotally mounted on a valve base 15.

Movement of the follower 13 is transmitted to a

valve stem

16, 17 of a hydraulic control valve 9 by a roller 18 carried on the arm 14. The valve stem is urged to the left, FIGURE 1, by the hydraulic pressure fluid; the valve controlling the impression mechanism of the printing press.

The end 17 of the valve stem passes through a back plate 19 fixed to the valve base 15. Pivotally mounted on the back plate 19, by a pin 21, is a latch plate 20, one end of which partly encircles an enlargement 22 of the valve stem 17.

The valve stem terminates in a head 23 of larger diameter than that of part 17, which is partly encircled by the latch plate.

An extension 24 of the latch plate carries an escapement member 25 which is pivotally mounted on a pin 25A. One end of a spring 27 is attached to a pin 26 secured to the latch plate, the other end of the spring is connected through linkage 28 to the core 29 of a solenoid 30.

The case and windings of the solenoid 30 are fixed to the back plate 19. A micro-switch 31 (normally closed) is so placed that it is opened When the latch is lifted. A further microswitch 32 (normally open) is closed when the core 29 of the solenoid rises upon energisation.

Referring to FIGURE 3, one end of the solenoid winding 30 is connected to one pole L of an electrical supply source and the other end of the winding is connected to three points, namely, one contact of the micro-switch 32, one contact of a one cycle button 33 and one of a pair of relay contacts 34 controlled by a coil 35 which also controls a pair of hold-on contacts 36.

The remaining contact of switch 32, the second contact of the one cycle button 33 and the other contact of the relay pair 34, are connected to the remaining pole N of the electric supply source through the normally closed off button.

The relay coil 35, when energised by depression of the on button, closes the

contacts

34 and 36 and is held on by contacts 36 when the button is released.

When the printing press is off impression the cam follower 13 rides on the raised part 12 of the cam 10. The solenoid 30 is de-energised and the latch 20 is as shown in FIGURES 1 and 2 behind the valve spindle head 23. When the cam rotates so that its follower is on the depressed part 11 of the cam the valve spindle 16, urged to follow the cam profile, is prevented from moving to the left FIGURE 1 by the latch.

When the on button 38 is pressed, relay 35 is energised and the contact 36 holds it on. The solenoid 30 is energised through the contacts 34. If the cam folllower 13 is on the raised part 12 of the cam, the latch is immediately raised through the spring 27 and when the cam rotates to allow the follower 13 to fall, the valve spindle 16 follows it and the impression mechanism operates. This cycle will continue until the off button 37 is operated when the contacts 34 and the solenoid are de-energised and the circuit returns to the off position. If, when the on button 38 is pressed the cam follower 13 is on the depressed part 11 of the cam, the latch 20 is trapped between the valve spindle head 23 and the back plate 19, and the solenoid will simply extend the spring 27. When the cam 10 has rotated so that the follower 13 is on the raised portion 12, the valve spindle collar 23 will be pushed away from the back plate 19 sufiiciently to release the latch and the latch will be drawn out of engagement by the spring. After this the impression mechanism operates the next time the depressed part of the cam comes round and each printing press cycle thereafter.

The mechanism thus ensures that the impression cylinder will only go on impression at the start of the next complete impression period after pressing the on impression button. When the solenoid 30 and the relay 35 are de-energised by pressing the off button 37, the latch drops immediately behind the valve spindle head 23 if the cam follower 13 is on the raised part 12 of the cam. If the cam follower is on the depressed part 11 of the cam, that is, during the impression stroke, the latch will ride on the periphery of the valve spindle head 23 until the valve spindle is pushed back by the cam follower when the latch will drop in between the valve spindle head and the back plate and lock the valve spindle. In this way the mechanism ensures that the impression cylinder will complete an impression stroke which is in progress at the time the off button is pressed.

For one cycle operation the one cycle button is pressed, the solenoid 30 only is energised but not the relay coil 35, and the solenoid holds itself on by closing the micro-switch 32. If the cam follower is on the raised part of the cam, the escapement 25 engages the valve spindle head 23 and prevents it from rising fully, although it releases the valve spindle. When the valve spindle head 23 moves to the on impression position, the escapement 25 is released, the latch is raised fully and opens the microswitch 31; this de-energises the solenoid 30 and allows the latch to fall. The latch is then trapped between the valve spindle head 23 and the back plate 19 on completion of the on impression stroke. In this way the impression cylinder will complete one full impression cycle after the one-cycle button 35 is pressed and will then return to the ofif im ression condition.

When the control system is to be applied to a two impression cylinder printing press, the second impression cylinder has its on-olf impression mechanism initiated at the same time as that of the first impression cylinder mechanism by contacts on the same push buttons or pedals. Whereas the first impression cylinder must commence its cyclic impression operations at the beginning of the cycle immediately following initiation, the second impression cylinder operation has to be delayed so that it commences its cyclic operation during the printing press cycle following that of the commencement of the operation of the first impression cylinder since any sheet printed during one cycle on the first impression cylinder is printed during the following cycle on the second impression cylinder. A similar delay is provided when the impression cylinders are taken off impression.

When the first impression cylinder impression is isolatedas by opening isolator switch 181 FIGURE 11, the second impression cylinder mechanism must continue to operate in the same time sequence as when the first impression cylinder mechanism is operative.

Likewise when the second impression cylinder mechanism is rendered inoperative as by opening isolator switch 182 FIGURE 11, the first impression cylinder mechanism will continue to operate in the same timed sequence as when the second impression cylinder mechanism is operative.

Referring to FIGURES 4 to 6, a camshaft 1 is rotated by mechanism, not shown, at a speed directly proportional to the printing speed of the printing press. Conveniently the camshaft makes one rotation to one complete printing cycle.

Secured to the camshaft is a cam 2, having a high portion 3 and a higher portion 4.

A rotary switch, generally designated 5, is secured to the camshaft 1, the rotary switch comprising two segments, a major segment 6 and a minor segment 107. The segment 107, subtends the same angle as a portion removed from the segment 6. The segment 6 has a brush contact L, and segment 107 has a brush contact S, the segments coming into contact with their respective contact during the rotation of the camshaft 1. Both segments, 6, 107, are electrically connected to a common brush contact C. The brush contact C is thus always in electrical contact with either brush contact L or brush contact S.

In this example the control valve 108 controls the hydraulic system operating the pull down of the second impression cylinder. The first impression cylinder has a pull down system controlled by the latch arrangement shown in FIGURES 1 and 2, the cams 2 andconveniently being mounted on the same shaft.

The hydraulic control valve 138 has a valve control spindle 109 which is resiliently urged towards the cam 2, so that when free to move one end abuts against the cam 2. Intermediate linkage similar to that employed between the cam and valve spindle in FIGURE 1 may be interposed between the cam 2 and the end of the spindle 109'.

The valve control spindle 141 9 has at the end remote from the cam 2 an enlarged diameter portion or head 110. The enlarged diameter portion may be placed in any convenient part of the valve spindle.

A latch 111, pivotally mounted at one end, to a part of the printing press, not shown, engages selectively on the spindle 109 adjacent the head 110'. If desired, instead of being pivoted, the latch may slide up and down in side members not shown.

The latch 111 is resiliently lifted by means of a solenoid S2 through a spring 112.

In certain positions the latch 111 can be locked against a lifting movement by the abutment therewith of the head 110, although the solenoid S2 is energised. In another position the latch may be dropped, but be prevented from latching in by the head 110 being positioned beneath the latch.

In the four conditions of the latch the following electrical contacts will obtain;

(1) The latch in the dropped position, but free to rise. Solenoid S2 de-e-nergised, switch M521 open and switch M322 closed.

(2) The latch in the dropped position, locked from lifting by abutment of the head v110, solenoid S2 energised, both switches MS21 and MS22 closed.

(3) The latch in the up position, solenoid S2 energised, switch MS21 closed, switch MS22 open, and

(4) The latch in the dropped position, but not locked because of the head 110, solenoid S2 d e-energised, switch M8 21 open, switch M822 closed. v i

The sequence of events in any given printing cycle are as follows;

(A) The first impression cylinder commences its impression cycle, and, at the same time the segment 7 breaks electrical contact with the brush contact S, and the brush cont-act L is engaged by the segment 6, so that the brush contacts L and C are electrically connected.

(B) Unless the latch 111 is in position to prevent it, the second impression cylinder commences its impression cycle.

(C) The second impression cylinder completes its impression cycle, the valve spindle 1179 being moved by the earn 2 to a position wherein the latch is free to latch in or out.

(D) The valve spindle 109 moves from the position at C to the normal off impression position, in which position the latch cannot engage if it is disengaged, nor disengage if it is already engaged.

'(E) The camshaft 1 has almost completed one revolution; the gap in the segment 6 breaks electrical contact between brush contacts C and L and the segment 167 completes electrical contact between brush contacts C and S.

The next cycle commences as at A.

This cycle of operation affects the impression cylinder impression electrical circuit as will be described. The control of the first cylinder impression circuit and its associated latch mechanism is the same as that described with reference to FIGURE 3. The appropriate references of FIGURE 3 have, however, been inserted in FIGURE 11. The only addition to the circuit shown in FIGURE 3 is the provision of the isolating switch 181 whereby the first impression cylinder can be stopped from going on impression without affecting the operation of the second impression cylinder.

It will be assumed that the printing press is running. Referring to FIGURE 11 the impression circuit on button closing contacts 38 and OB, is pressed at any time during the cycle A to E outlined above. The closing of the contacts OB of the second impression cylinder circuit energises a relay R2, which is held on by contacts R21, and at the same time closes contacts R22.

The first impression cylinder will go on impression at the completion of the stage E of the cycle and the start of the second cycle. Since, at this position, the contact S is in electrical contact with the contact C, the solenoid S2 will be energised, its armature closing the microswitch M521, thereby putting the contact L in circuit.

The second impression cylinder is, however, held off impression as the first impression cylinder comes on impression and the control mechanism has the relative positions shown in FIGURE 4. The solenoid S2 has been energised, closing the switch M521 and putting the contact L in circuit, but the latch 111 is prevented from rising by the action of the head which is bearing on it. Thus the valve spindle 109 cannot move towards the cam 2 and no on impression stroke will be initiated.

When rotation of the camshaft moves the segment 107 off the contact S, the circuit is not broken through the solenoid S2, since the contact L has been placed in circuit .by the closing of the switch M321.

Just after the end of the first impression cylinder impression stroke the high part 4 of the cam 2 moves the valve spindle 10) so that the latch 111 is free to rise under the action of the solenoid S2 which has extended the spring 112, and the condition shown in FIGURE 5 obtains. In this position the latch is held out and the valve mechanism will be purely cam operated.

From the foregoing it will be seen that a sheet fed to the first impression cylinder, which has had the impression circuit closed at any time during the sequence A to E above, will be printed during the second cycle thereof and transferred to the second impression cylinder for printing during the third cycle of the printing press.

When the off button 137 is pressed at any time in the cycle A to E above, the first impression cylinder will complete its impression stroke and then come off impression. However, the pressing of the off button will de-energise the relay R2, which will open the contacts R21, R22, and the solenoid S2 will be de-energised at the beginning of the next impression cycle when the segment 107 contacts contact S and the valve spindle is on the portion 3 of the cam 2. The armature of the solenoid S2 will drop the latch, opening the switch M821, putting the contact L out of circuit. But the relationship between the cam 2 and the valve spindle 9 (see FIGURE 6) is such that the head 110 prevents the latch from dropping in, and the second impression cylinder will complete its impression cycle, at which point the latch will drop in and the impression cylinder will be held in the off impression condition.

A one cycle operation is effected by depression of the one cycle button which operates contacts 33 and OS. The first impression cylinder will then print a single impres sion and the sheet will be passed to the second impression cylinder which will in its turn print a single impression.

Contacts OS energise the relay R3, which closes contacts R31, R32 and is held energised by the contact R31. The contact S is also put into circuit through the contact R32. At the beginning of the first impression cylinder impression stroke the contact S is electrically connected to the contact C, the solenoid S3 is energised, the armature of which closes the switch M821, and the contact L is put into circuit. At this point the latch is not free to lift, as it is retained by the head 110 of the spindle 9, and the spring 112 will be extended.

On continuation of rotation of the camshaft, the contact S is moved out of circuit, and the contact L comes into circuit with the contact C and the solenoid S2 remains energised.

The high part 4 of the cam 2 then moves the valve spindle to release the latch 111, which rises and opens the switch M822. Opening of the switch M822 deenergises the relay R3, which opens the contacts R32, putting the contact S out of circuit.

The camshaft continues to rotate and electrical contact between the contacts C and L is broken. The contact C is then put in circuit with contact S, but contact S is out of circuit, the solenoid S2 is de-energised, allowing the latch to drop, opening the switch MS21, and putting the contact L out of circuit.

The latch cannot at this point engage the valve stem, the stem at this point being cam controlled, because of the head 110. Thus the second impression cylinder will complete its impression cycle and will then automatically come off impression.

In the foregoing example the hydraulic control valve 108 is shown as a piston type valve. In the example shown in FIGURE 9 a rotary plug type valve 113 for controlling the hydraulic system for impression cylinder pull down is used.

Mounted on the valve plug spindle 114 is a substantially triangular plate 115 having a cam roller 116 at one apex and a step 117 at another apex. The step 117 is the equivalent of the head 110 on the valve spindle 109 of the previous example, FIGURES 4 to 6.

The cam 2 and rises 3, 4 are identical with those of the previous example, likewise although the latch 111 of the previous example has been replaced by a plunger 118 supported in a guide 119, the solenoid S2 and spring 112 are identical.

The triangular plate 115 is resiliently urged towards the cam 2 by a spring 120, anchored to the plate 115 at one end and to a convenient stationary part of the printing press, not shown, at the other end.

The function and operation of this example are identical with that of the previous example and need no further description.

In FIGURE there is shown a third modification in which a cam 121 is used to operate, through a trip linkage, a master cylinder 122. The cam 121 is rotated at a speed directly proportional to the printing speed of the printing press.

Rotation of the cam 121 effects oscillation of a lever 123, pivotally mounted at one end on a pivot pin 124 secured to the frame of the printing press, not shown. The cam 121 has a high portion 125 which swings the lever 123 clockwise, FIGURES 7 and 10, so that when an interposer 126 is in the position shown in FIGURE 10, swing of the lever 123 will swing a lever 127, pivotally mounted on the pin 124 and force the piston rod 122 of the master cylinder into the cylinder, forcing hydraulic fluid under pressure therefrom.

The hydraulic fluid from the master cylinder is pumped through a pressure relief valve 128 into the impression cylinder pull down rams 129.

The volume of hydraulic fluid displaced by the master cylinder 122 is slightly larger than the combined volumes of the rams 129, so that after the rams have been extended the excess hydraulic fluid will be exhausted through the pressure relief valve 128 to a reservoir 40, thus ensuring that the requisite pressure is attained and retained during an operative stroke of the rams.

The profile of the portion 125 of the cam 121 is preferably such that during the on-impression period a further slight excess is pumped to ensure maintenance of pressure in the rams.

A pressure gauge 41 is connected by a branch pipe from the pipe supplying the hydraulic rams, a non-return valve 42 being interposed in the branch pipe; the full pressure in the pipe supplying the hydraulic rams 129 reaches the gauge 41.

A slow bleed return valve 43 prevents violent fluctuations of the pressure gauge needle.

Continued rotation of the cam allows the lever 123 to swing back to the position shown in FIGURE 10. This return movement is assisted by the pressure in the system, forcing the piston rod from the master cylinder, and by a spring 44.

After the hydraulic rams 129 are completely retracted, further movement of the master cylinder 122 will cause hydraulic fluid to be drawn from the reservoir 40 through a non-return valve 45 to the master cylinder. The volume of this make up fluid will be equivalent to the amount expelled through the relief valve 128 during an operative stroke of the master cylinder.

The control means for this system are shown in FIG- URE 7; the electrical circuit is the same as that already described with reference to FIGURE 11.

In FIGURE 7 like references have been used for like parts already described; the sequence of operation being substantially identical with that already described, a detailed description will not be given.

Referring to FIGURE 7, the lever 123 will oscillate under the influence of the cam 121, and will rock the lever 127 positively clockwise (FIGURE 7) when the interposer 126 is lifted to a position between the lever 123 and a curved tail 127' of the lever 127.

The interposer 126 is the equivalent of the latch 111 of the example hereinbefore described with reference to FIG- URES 4 to 6, and fulfills exactly the same functions at exactly the same times, that is, when dropped, as shown in FIGURES 7 and 8 the system is inoperative, this being the equivalent of the latched in condition. In this position the lever 123 can oscillated freely without actuating an operative stroke to the master cylinder 122, the tail 127' passing freely through a hole 123 in the lever 123. The cam stroke is such that the highest point of the cam will not abut directly against the end of the tail 127.

When the solenoid S2 is energised the spring 112 will attempt to pull up the interposer 126 which cannot rise until the lever 123 has moved its full extent anti-clockwise (FIGURE 7), which condition is the equivalent of that described with reference to FIGURE 4.

When the solenoid S2 in the energised condition and the interposer 126 has risen, the condition shown in FIG- URE 10 obtains, and the system will be controlled directly by the cam 21; the equivalent condition of that described with reference to FIGURE 5.

When the solenoid S2 is de-energised, the interposer 126 will try to drop out, but will be frictionally retained between the tail 127' and the lever 23 until the end of a return (anti-clockwise in FIGURE 7) movement of the

levers

23, 27. This is the equivalent condition of that described with reference to FIGURE 6.

It will be appreciated that the system shown in FIG- URES 7 and 10 is applicable to a single impression cylinder printing press as well as a two impression cylinder printing press, in which instance, as shown in FIGURE 7, an escapement 46 is provided on the interposer 126, the escapement being pivotally mounted thereon. The escapement is so shaped that when the interposer 126 is raised the microswitch M522 will not be opened; the microswitch will only be opened towards the end of an operative stroke of the arm 123, when the escapement 45 abuts against a fixed abutment 47, causing it to swing about its pivot and open the microswitch contacts. The electrical circuits effected by the operation of the microswitch are as hereinbefore described with reference to FIGURE 3.

In the foregoing examples the control system has been described with reference to a two colour printing press. By suitable retiming the control system can be applied to a perfector printing press in which the delay between the impression cylinders coming on-oif impression must be timed to occur at a half printing cycle difference.

The electrical circuit shown in FIGURE 11 clearly divides the first and second impression cylinder control circuits, but other electrical arrangements are possible in which components common to both impression cylinders may be shared.

What we claim is:

l. A control system for the impression mechanism of the impression cylinder of a printing press provided with a cam driven in synchronism with the printing press drive, said control mechanism comprising a valve controlling the impression mechanism, which valve has a spindle normally urged to the on impression position, a locking mechanism including a latch for retaining the valve spindle in the oil impression position and means to release the lock, the cam during part of its movement thrusting the valve spindle to an off impression position and allowing the spindle to return to the on impression position during the remainder of the cam movement, the latch being held out during printing operations to allow of cyclic movement of the valve spindle, the dropping of the latch becoming effective to lock the valve spindle in the off impression position when the valve spindle is thrust into that position by the cam, the valve spindle being latched thus even on actuation of the latch lifting means until the off impression portion of the cam is in the operative position relative to the valve spindle, whence the latch will lift, the arrangement being such that the valve spindle will be locked in the oil impression position until the correct timing sequence for a complete printing cycle obtains.

2. A control system according to claim 1, wherein the valve stem is reciprocated in the on-otf impression control cycle.

3. A control system according to claim 1 wherein the valve stem is oscillated in the on-oti impression control cycle. 1

4. A printing press including, in combination, a power drive, an impression cylinder movable to anon and off position alternately during each complete printing cycle, hydraulic operating mechanism for efifecting such on and off movements of the impression cylinder automatically at the proper times in the printin cycle, and a control system for said mechanism comprising a hydraulic valve operated by and in synchronism with the press drive to control the operation of said hydraulic mechanism in effecting the cyclic on-oif impression movements of the impression cylinder, said valve being normally urged to an oil-impression control position, and means operated in synchronism with the press drive for retaining the hydraulic valve temporarily in an oil-impression control position until the correct time has been reached in a complete printing cycle for the on-impression movement of the impression cylinder and for then permitting the valve to assume its on-impression control position for effecting the on-impression movement of the impression cylinder.

5. A printing press according to claim 4 wherein the means for retaining the valve in an oil impression control position comprise a latch adapted to releasably engage the valve stem in such position of the valve.

6. A printing press according to claim 5 wherein the latch is controlled by means adapted resiliently to lift the latch to give freedom of movement to the valve stem when the correct time has been reached for the onimpression movement of the impression cylinder, which lifting means although energised cannot release the latch from the valve stem until such correct time.

7. A printing press according to claim 6, wherein the latch is lifted by means of a solenoid through a resilient coupling with the latch.

8. A printing press according to claim 7 wherein the latch is provided with a pivoted pawl to abut against the valve stem and prevent latch movement, when the valve stem is in the oil impression position, and the latch lifting means energised by the solenoid, thereby preventing self cancelling means from dropping the latch until a single complete cycle of printing has taken place.

9. A printing press including, in combination, a power drive, two impression cylinders operating in timed relation to each other and each movable to an on and off position alternately during each complete printing cycle entailing the revolution of both cylinders, two hydraulic 16 operating mechanisms for effecting such on and oil movements of the two impression cylinders automatically at the proper times in a complete printing cycle, and two control systems, one for each impression cylinder operating mechanism, operating in the same timed relation to each other as the impression cylinders, each of said control systems comprising means operated in synchronism with the press drive for locking out the on-impression movement of the corresponding impression cylinder until the correct time for such movement has been reached in a complete printing cycle, characterized in that there is provided a valve controlling the hydraulic operating mechanism of the second impression cylinder, which valve has associated therewith means for effecting cyclic operation of the valve to efiect on-oif impression movements through the operating mechanism to the second impression cylinder and means for holding the valve in the off impression controlposition until the correct timing sequence for the second impression cylinder in relation to the first impression cylinder and to a complete printing cycle of the printing press obtains.

10. A printing press according to claim 9 wherein there is provided latch means for retaining the stem of the valve in an oil impression control position.

11. A printing press according to claim 10 wherein the latch is controlled by means adapted resiliently to lift the latch to give freedom of movement to the valve stem, which means, although energised, cannot release the latch from the valve stem until synchronism between the two impression cylinders obtains in relation to a complete printing cycle of the printing press.

12. A printing press according to claim 9 wherein the valve is operated to an oil-on impression control cycle by cam means rotated in synchronism with the printing press drive, which carn means act on the valve stem to effect movement thereto, and hence the control of the impression mechanism of the second impression cylinder of the printing press.

13. A printing press according to claim 11 wherein the latch is lifted by means of a solenoid through a resilient coupling with the latch.

14. A printing press according to claim 9 wherein there is provided a multi-contact rotary switch operating in synchronism with the printing press drive in fixed relationship with the second control means, which switch controls the circuits for energising the latch lifting means.

15. A printing press including, in combination, a power drive, to impression cylinders operating in timed relation to each other and each movable to an on and off position alternately during each complete printing cycle entailing the revolution of both cylinders, two operating mechanisms for effecting such on and off movements of the two impression cylinders automatically at the proper times in a complete printing cycle, and two control systems, one for each impression cylinder operating mechanism, operating in the same timed relation to each other as the impression cylinders, each of said control systems comprising means operated in synchronism with the press drive for locking out the on-impression movement of the corresponding impression cylinder until the correct time for such movement has been reached in a complete printing cycle, characterized in that the control system for the second impression cylinder also comprises a rotary switch rotating in synchronism with the press drive, a valve controlling the on-oif impression strokes of the impression mechanism of the second impression cylinder, the valve spindle being normally urged into the on impression control position, a latch adapted to engage the valve spindle to hold the valve in an off impression control position, and means controlled by the rotary switch for resiliently lifting the latch to release the valve stem, such release being effected only when the valve stem is cammed to a release position, the relationship of movements of the cam, rotary switch, valve and latch being such that on the closure of the circuit to commence a printing cycle, the

second impression cylinder will be held off impression until the correct timing sequence relatively to the first impression cylinder and to the commencement of a complete printing cycle has been obtained.

16. A printing press including, in combination, a power drive, an impression cylinder movable to an on and OH? position alternately during each complete printing cycle, hydraulic operating mechanism for effecting such on and oif movements of the impression cylinder automatically at the proper times in the printing cycle, and a control system for said mechanism comprising a hydraulic valve operated by and in synchronism with the press drive to control the operation of said hydraulic mechanism in effecting the cyclic on-oit impression movements of the impression cylinder, and means for retaining the hydraulic valve in an off-impression control position until the correct time has been reached in a complete printing cycle for the on-impression movement of the impression cylinder, said means for retaining the valve in an off impression control position comprising a latch means adapted to releasably engage the valve stem, characterized in that the control system includes an electric circuit comprising a relay, energised by the closure of a switch, a solenoid contact closed by the energisation of the relay and a solenoid, the closure of the solenoid contact energising the solenoid to put the latch in a condition of lifting to release the valve stem.

17. A printing press including, in combination, a power drive, an impression cylinder movable to an on and oif position alternately during each complete printing cycle, operating mechanism for effecting such on and ed movements of the impression cylinder automatically at the proper times in the printing cycle, and a control system for the impression cylinder operating mechanism comprising a first means controlling the cyclic on-ofi impression movements of the impression cylinder, and second means operated in synchronism with the press drive for locking the first means in an off-impression condition until the correct time has been reached in a complete printing cycle for the on-impression movement of the impression cylinder, characterized in that the first means of the control system is mechanically operated from the press drive, and in that the second means of the control system is partly mechanical and partly electrical, the electrical portion of the second means of the control system including an on-switch and an off-switch to activate and deactivate said second means, respectively, and the electrical portion of the second means of the control system including a one-cycle switch which starts the machine at any point in a complete printing cycle, allows the machine to operate without printing until the correct time in a complete printing cycle has been reached for the on-impression movement of the impression cylinder, and thereafter initiates the operation of the press for one complete printing cycle.

18. A printing press including, in combination, a power drive, an impression cylinder movable to an on and off position alternately during each complete printing cycle, hydraulic operating mechanism for effecting such on and off movements of the impression cylinder automatically at the proper times in the printing cycle, and a control system for said mechanism comprising an automatically operated hydraulic control member movable alternately to an on-impression control position and to an ofi-impression control position during each normal printing cycle in effecting the cyclic on-ofif impression movements of the impression cylinder, and automatic means operated in synchronism with the press drive and acting (l) to retain the hydraulic control member temporarily in an oil?- impression control position until the correct time has been reached in a complete printing cycle for the on-impression movement of the impression cylinder and (2) to release the control member and permit it to move to its onimpression control position at the correct time for the on-impression movement of the impression cylinder in said printing cycle.

19. A printing press according to claim 16 wherein the electric circuit includes a hold on contact closed by the relay to maintain the circuit closed.

20. A printing press according to claim 16 wherein the electric circuit includes a one cycle control comprising a one cycle operating switch, a switch normally open, a switch normally closed and the latch lifting solenoid, the closure of the one cycle switch energising the latch lifting solenoid, the movement of which solenoid closing the open switch to maintain the circuit closed and the lifting of the latch opening the closed switch to break the circuit and to de-energise the solenoid.

21. A printing press according to claim 16 wherein the electric circuit includes, for the control of the impression movements of a second impression cylinder, a relay, energised by the closure of a start switch, a hold on contact, and a contact, both contacts being closed on energisation of the relay, the contact including a brush in circuit preparing the circuit for closure by a rotary switch having a plurality of interrupted contacts one of which interrupted contacts contacting the brush will complete the circuit, energising the latch lifting solenoid to resiliently lift the latch ofi? the valve stem of the valve controlling the impression mechanism of the second impression cylinder.

22. A printing press according to claim 21 wherein the energisation of the solenoid closes a contact putting into circuit another brush engaging another interrupted contact on the rotary switch, thereby maintaining the solenoid in an energised condition.

23. A printing press according to claim 21 provided with a one cycle impression control including a switch, and a relay closing a hold on contact and closing a contact putting into line a brush of the rotary switch, which rotary switch at a given period will complete a circuit through the solenoid, which, thus energised, attempts to lift the latch, the movement of the solenoid closing a switch putting another brush of the rotary switch into line, continued rotation of the rotary switch breaking the first brush contact, the solenoid remaining energised through the second brush and contact, the latch when raised opening a switch to de-energise the relay and cut the first brush out of the line, continued rotation of the interrupted contacts of the rotary switch breaking contact with the second brush, opening the circuit and thus de-energising the solenoid allowing the latch to drop.

References Cited in the file of this patent UNITED STATES PATENTS 1,081,320 Miehle Dec. 16, 1913 1,192,133 Stevens July 25, 1916 2,216,565 Eckhard Oct. 1, 1940 2,335,010 Huck Nov. 23, 1943 2,419,403 Horton Apr. 22, 1947 2,950,674 Taylor et al. Aug. 30, 1960

Claims

4. A PRINTING PRESS INCLUDING, IN COMBINATION, A POWER DRIVE, AN IMPRESSION CYLINDER MOVABLE TO AN ON AND OFF POSITION ALTERNATELY DURING EACH COMPLETE PRINTING CYCLE, HYDRAULIC OPERATING MECHANISM FOR EFFECTING SUCH ON AND OFF MOVEMENTS OF THE IMPRESSION CYLINDER AUTOMATICALLY AT THE PROPER TIMES IN THE PRINTING CYCLE, AND A CONTROL SYSTEM FOR SAID MECHANISM COMPRISING A HYDRAULIC VALVE OPERATED BY AND IN SYNCHRONISM WITH THE PRESS DRIVE TO CONTROL THE OPERATION OF SAID HYDRAULIC MECHANISM IN EFFECTING THE CYCLIC ON-OFF IMPRESSION MOVEMENTS OF THE IMPRESSION CYLINDER, SAID VALVE BEING NORMALLY URGED TO AN ON-IMPRESSION CONTROL POSITION, AND MEANS OPERATED IN SYNCHRONISM WITH THE PRESS DRIVE FOR RETAINING THE HYDRAULIC VALVE TEMPORARILY IN AN OFF-IMPRESSION CONTROL POSITION UNTIL THE CORRECT TIME HAS BEEN REACHED IN A COMPLETE PRINTING CYCLE FOR THE ON-IMPRESSION MOVEMENT OF THE IMPRESSION CYLINDER AND FOR THEN PERMITTING THE VALVE TO ASSUME ITS ON-IMPRESSION CONTROL POSITION FOR EFFECTING THE ON-IMPRESSION MOVEMENT OF THE IMPRESSION CYLINDER.