US2261913A - Printing press - Google Patents

Description

Nov. 4; 1941.

W. W. DAVIDSON, JR., ET AL PRINTING PRESS Filed Jan. 28, 1939 7 Sheets-Silesia l PRINTING PRESS Filed Jan. 28, 1939 '7 Sheets-Sheet 2 Nov. 4, 1941- w. w. DAVIDSON, JR., ETAL 2,251,913

PRINTING PRESS Filed Jan. 28, 1939 7 Sheets-Sheet 3 Nov. 4, 1941.

w. w. DAVIDSON, JR; ETAL PRINTING PRESS Filed Jan. 28, 1939 7 Sheets-Sheet 4 mm i111 Illl 1941. w. w. DAVIDSON, JR, ETAL PRINTING PRESS 7 sheets-sheet 5 Filed Jan. 28, 1939 m M V Q V v I. v a 1' f v I o a V v 1 2.

Nov. 4, 1941. 'w. w. DAVIDSON. JR., ETAL 2,251,913

PRINTING PRESS Filed Jan. 28, 1959 7 Sheets-Sheet 6 .IIH In HUM Nov. 4, 1941. w. w. DAVIDSON, JR, ETAL 2,251,913

- PRINTING PRESS Filed Jan. 28, 1959 7 Sheets-Sheet 7 liwantors Patented Nov. 4, 1941 PRINTING PRESS William Ward Davidson, Jr., Niles Center, and Edward Frank Dell, Park Ridge, 111., assignoi's to Davidson Manufacturing Corporation, a corporation of Illinois Application January 28, 1939, Serial No. 253,292

17 Claims.

In printing by the offset method there are three main drums or rolls. A blanket roll or printing drum rotates in contact with the plate roll, receives the ink therefrom and prints it on the sheet being printed, and a third roll called the platen presses the sheet against the blanket roll. For high quality printing it is of course necessary that the contacts between each pair of rolls be delicately and accurately adjusted. On the other hand, it is important that when no sheet is fed to the blanket and platen rolls for printing, these rolls should be separated so that the platen will not contact the inked portion of the blanket roll since the ink thus transferred to the platen would be printed on the backs of the sheets subsequently printed. It is also highly desirable that when no sheet is fed to the blanket roll and platen, the blanket roll and plate roll be separated so that no excess of ink will be applied to the blanket roll.

An object of the invention is to provide very simple and satisfactory means for separating the blanket roll from both the plate roll and the platen roll if no sheet is being fed to the blanket roll and platen at the proper time. This is accomplished very simply according to the present invention by so mounting the blanket roll that upon simply releasing a latch the blanket roll will move in a direction away from both the plate roll and the platen. If automatic operation is desired, it may be provided by having a feeler at the feeding position moved in synchronism with the blanket roll and automatically releasing the latch when no sheet is at the feeding position at the proper time. This system lends itself admirably to various other advantages, the provision of which may be considered additional objects of the invention.

The latching device may be connected with a control switch so that the press will be stopped automatically when the blanket roll is separated from the other rolls or thrown out. This is desirable because with a good automatic preliminary feeder the absence of a sheet at the final feeding position probably indicates that the supply of sheets has been exhausted. The interconnection of the latch and the switch also is advantageous in .that the press will automatically be started when the latch mechanism is operated to begin the retumof the blanket roll to its active position. The latch may also be used for controlling the sheet counter so that, when the latch is automatically released because no sheet is being fed, the counter will cease to count.

the contact adjustment system so that neither will interfere with the other and so that some parts will be used in common. An eccentric shaft has been found very satisfactory for both purposes. It also lends itself to the use of special couplings between the gears and the rolls which permit the gears to be journaled about fixed axes so that they will always mesh properly. A universal or variable-axis coupling may therefore be provided between the driving gears and both th blanket roll and the platen roll and that of the blanket roll will serve to permit both the contact adjustments and the throw-out movement.

Additional advantages and objects of the invention will be apparent from the following description and from the drawings, in which:

Fig. 1 is a perspective view of a press chosen for illustration of this invention with parts broken away for the sake of clarity.

Fig. 2 is a side elevation of the structure shown in Fig. 1 with the blanket roll in thrown-out position.

Fig. 3 is a corresponding view showing the blanket roll in operative position.

Fig. 4 is a fragmentary sectional view taken approximately on the line 4-4 of Fig. 3.

Fig. 5 is a fragmentary longitudinal sectional view showing particularly the automatic control device. I

Fig. 6 is a fragmentary view diagrammatically illustrating the drive for the preliminary feeder.

Fig. '7 is a fragmentary horizontal sectional view taken approximately on the line ll of Fig. 2.

Figs. 8 and 9 are diagrammatic views illustrating the relations of the centers and the dispositions of the various eccentrics.

A preferred embodiment of, the invention has been shown in the drawings and will hereinafter be described all as required by section 4888 of the Revised Statutes, but the invention may take numerous forms.

The invention has been illustrated as embodied in an ofiset printing press in which the actual printing is performed by a blanket roll I I against which the sheet is fed by a platen ii. The blanket roll II is covered with a smoothsurfaced blanket iii of rubber or the like which receives the ink from a plate roll it. Of course, suitable inking rolls, not shown, must be provided for the plate roll. It will be understood that these three main rolls or drums are geared together to rotate at the same peripheral speed The throw-out system can be combined with so that the plate roll prints onto the blanket l3 which in turn prints onto a sheet fed between the blanket roll I l and the platen l2.

It is customary .to feed the sheets to the printing rolls II and I2 in timed relation therewith automatically so that with each revolution of the blanket roll H a sheet will be inserted at the proper time for printing. This feeding mechanism may include a separating roller i6 (Fig. for separating a sheet from a stack, and a conveyor I! which delivers the sheet against stop fingers l8 but which is also laterally biased to urge the sheet against a side guide 18 to secure lateral registry thereof. The stop fingers l8 comprise a portion of the final feeding and registering mechanism, which also includes the feed rollers 2|, the pressure roller 22 and the mechanism for operating these devices.

Although any feeding mechanism might be used with the present invention, an understanding of the feeding mechanism may help in obtaining an understanding of the present inven tion. The separating roller I6 is driven intermittently by a reciprocating rack 26 (Fig. 6) and pinion 21 bywhich the roller I6 is driven through an overrunning clutch represented by the rollers 28. The rack 26 reciprocates for each revolution of the blanket roll being driven, as illustrated diagrammatically in Fig. 6, by means eccentrically connected to some member 29 rotating in unison with the blanket roll. The separating roller |6 feeds a, sheet to the conveyor l! on which it is gripped by a pressure roller 3| and fed against the stop fingers l8 and the side guide |9. While the stop fingers l8 and feed rollers 2| are stationary and while the sheet is at rest against the stop fingers l8, the pressure roller 22 is lowered by action of cam 32 so that the sheet is firmly gripped between the pressure roller 22 and the feed rollers 2|. Immediately thereafter, cam 33 operates gear segment 34 to rotate feed roller 2| to feed the sheet to the bite between blanket roll II and the platen l2. The shape of the cam 33 is such that at the time the sheet reaches the bite it is moving at the peripheral speed of these printing rolls. Immediately thereafter, the pressure roller 22 is released by cam 32 so that the sheet may be drawn freely through the feeding mechanism. The cycle is completed by a return of the feed roller 2| and fingers l8 to their initial position under influence of the return spring 36, which incidentally eliminates all slack or play from the drive of the feed roller 2| so that the feeding of the sheet is absolutely uniform.

Whenever the stack of sheets runs out and perhaps on rare other occasions due to some failure of the mechanism, there will be no sheet on the final feeding table 31 to be fed by the roller 2| to the printing rolls H and I2. If these rolls are permitted to rotate in contact with one another when no sheet is fed thereto, the ink from the blanket l3 will be printed on the platen l2. It is obvious that this is very undesirable, one reason being that the ink on the platen |2 would be printed on the reverse side of the next sheets fed with the result that such sheets would be ruined. It has been common heretofore to provide means for separating the two printing rolls corresponding to the blank roll II and the platen l2, This separation is called a throw-out. Sometimes the expression platen throw-cu is used because originally the platen was the roll which was moved.

In the present instance the blanket roll II is moved and therefore the expressions blanket roll throw-cu and impression roll throwout would be more appropriate. The term "printing roll throw-out could be used to describe the movement of either of the rolls.

It is highly desirable to accomplish the throw-out by means of moving the blanket roll II in a direction away from both the platen l2 and the plate roll -|4. The reason is that this throw-out will separate the blanket roll H from both of these other rolls so that if printing is promptly resumed the blanket roll II will be in condition to print properly immediately. If it were left in contact with the plate roll |4 while the press rotated without supplying sheets to be printed, the plate roll |4 would transfer an excess of ink to the blanket 3 and hence the initial subsequent printing would be unsatisfactory.

Throw-out mechanism Complicated mechanisms have been provided heretofore for causing the blanket roll II to move away from both rolls l2 and I4. According to the present invention this is accomplished very simply. As shown roughly in Fig. 1, the blanket roll rotates on a shaft portion 4| which forms an eccentric part of shaft 42 journaled in the press frame 43. The shaft 42 may be provided with a handle 44 by which the shaft 42 may be turned with the result that its eccentric portion 4| will move the blanket roll toward or from the platen l2 and plat-e roll l4. This eccentric mounting is seen best in Fig. 4 and is described in detail subsequently.

The shaft 42 also carries a lever 46 which may be called a latch lever or a throw-out lever. When the blanket roll I is in its thrown-out position as seen in Fig. 2, the latch lever 46 is not latched but is held in this position by a throw-out spring 41 which urges the lever 46 against a stop 48 preferably having a rubber collar 4!!v for absorbing shock as the lever 46 is slammed against it. When the press is to be operated, the handle 44 is turned in a couterclockwise direction until the latch lever 46 is caught in front of a ratchetshaped lug 5| on a pivoted latch arm 52 which is urged upwardly by a spring 53. With the parts in this position, as shown in full lines in Fig. 3, the blanket roll I I will be in contact with the plate roll l4 and the platen |2 or, in other words, the press will be in operative condition.

Whenever there is no sheet in position to be fed to the printing rolls H and I2, a throw-out may be accomplished with extreme ease and rapidity merely by thrusting the latch arm 52 downwardly. For this purpose a handle 54 is provided thereon. As soon as the latch arm 52 is pivoted downwardly enough to permit the latch lever 46 to clear the lug 5|, the spring 41 will snap the lever 46 against the'stop 48, thus turning shaft 42 and shifting its eccentric portion 4| to move the blanket roll II to the position seen in Fig. 2.

Motor control It will be observed that the latch arm 52 has been illustrated with a second ratchet-shaped lug 56 thereon. This serves a very useful purpose in that it aids the latch lever 46 to control a switch 51 for starting and stopping the press.

When the latch lever 46 is first moved to be engaged by the lug 56, it starts the motor and not until its final movement to the lug 5| is the blanket roll I I brought in contact with the platen l2 and plate roll N. The latch lever 46 is connected with .the motor switch 51 by means of a rod and a bell crank 59 which it operates through a coupler 60 swiveled to the bell crank. The bell crank 59 has a slotted engagement with the toggle lever SI of the switch 51. In Fig. 2 toggle lever 6| has been shown in the off position. It is thrown to the on position of Fig. 3 by action of a spring 62 bearing at one end against a pin 63 carried by rod 58 and at the other end against the coupler 60. The rod 58 extends through the coupler 60 and is slidable with respect thereto 50 as to leave the rod 58 free to move after the toggle 6i has reached the limit of its movement. Thus, as the latch lever 48 is moved to the intermediate position in engagement with the lug 56, the rod' 58 and the spring 62 turn the bell crank lever 59 to snap the toggle Si to turn on the motor and start the press. When the press has obtained the proper speed. the latch lever A6 is turned further to engage the ing This in turn moves the rod 58 further but, since the bell crank 59 cannot turn further. the rod 58 slides in coupler 60, thus merely compressing the spring 62. A cotter pin 65 is secured in the end portion of the rod 58 so that when the latch arm 52 is released and the latch lever 46 is sprung back to the position shown in Fig. 2, the cotter pin 66 (or a washer) will engage the coupler 66 of the bell crank 59 and rotate this lever to shift the toggle back to the "off position shown in Fig. 2.

Automatic throw-out It will be observed that the throw-out and motor control mechanism described to this point are independent of the feeding mechanism and could even be used when the sheets are fed mainly by hand. In this form the throw-out mechanism is very simple and economical to manufacture although it is entirely manually operated. When cost considerations will permit, an automatic throw-out operation is very desirable, and, since the illustrated form of throw-out mechanism lends itself admirably to automatic operation, a structure for providing such automatic operation has been illustrated.

The latch arm 52 may be mounted on a shaft 7 i on which in turn may be mounted a release arm l 72 having a lug 13 positioned just below the top of feeding table 3? which is provided with a slot i i to expose the lug l3 therethrough. When no sheet is in place it will be possible for a feeler 75 to pass into the slot it and engage the lug 13. The feeler i5 is reciprocated intimed relation with the blanket roll ii so that it moves forwardly just as the printing of one sheet is finished and another sheet should be in the feeding position. If the sheet is there, the feeler will be held up above the table 31 out of contact with the release arm i2. If no sheet is present, the feeler 15 will dip into the slot 14, engage the lug l3 and operate the release arm 72 and the latch arm 52' to release the lever 46 so that the spring 5? will sap the latch lever 46 against the stop d8, thus throwing out the blanketroll II.

Although the feeler 15 may be reciprocated in any suitable manner, it has been illustrated as operated by the cam 33 which also operates the feed roller 2|. This operation is by means of .a link 16 swiveled to and connected between the arm 17 and a crank arm I8 mounted on shaft 19 which carries another crank arm to which thefeeler i5 is pivoted. A special return spring may be provided or spring 38 may be relied upon.

Adjustment of printing rolls Although the foregoing structure may be used with a variety of forms of mounting and adjustment means for the printing rolls. it lends itself admirably to the simplified and extremely convenient structure shown in Fig. 4.

There are two adjustments necesary between every pair of printing rolls. On is the adjustment for uniformity of pressure along the line of contact and the other is the adjustment for the amount of pressure. The adjustment for uniformity of pressure is a relatively fixed adjustment and is necessary usually to compensate for inevitable inaccuracies in the manufacture of the press. According to the present invention the uniformity of pressure is produced by eccentric bushings which shift one end of each shaft on which a roll to be adjusted is mounted. In the case of the blanket roll II this shaft is the shaft 42. This shaft 52 is provided with a stub extension 93 which is journaled in an eccentric bushing 89 (Figs. 4, 8 and 9) which is rotatabiy carried by the press frame 63. In other words, th rotatable bushing 89 is provided with an eccentric hole in which the stub 83 of the shaft 62 is journaled. The bushing 84 is preferably provided with a lever 86 which permits rotation of the bushing to shift the stub shaft 83. The press is designed so as to have the bushing 85 initially at such angular position that its rotation will move the stub shaft 83 either directly toward or directly from the plate roll i i. This positioning is seen best in Figs. 8 and 9, in which it is seen that line A-B from the center A of bushing M to center B of stub shaft 83 is perpendicular to the line B-C, C being the axis of plate roll it. Thus, if the pressure of the plate roll it at the side of the blanket roll H near th lever 85 is lighter than at the other side, the lever 96 and its bushing 86 will be turned in a direction to move the stub shaft 83 toward the plate roll is and increas the pressure at this side. When an adjustment providing uniform pressure has been obtained, a screw 88 passing through a concentric slot 99 in lever 86 may be tightened to lock the bushing 84 in this adjusted position. The lever 96 may have a handle 90.

In order to alin the platen i2 with blanket roll ii so as to provide uniform pressure along their lin of contact, a bushing 9i similar to the bushing 8% may be provided. In this bushing is journaled a shaft 92 on which the platen i2 rotates, the journaled portion of the shaft 92 being eccentrically positioned in the bushing 9| as was the case of the stub shaft 83 in the bushing 85. A handle 93 is preferably provided for turning the bushing 98 so as to provide uniform pressure along the line of contact between the platen i2 and the blanket roll ii. When this uniform pressure has been attained, a screw -96 may be tightened to maintain th adjustment.

It will be noted that at the other end of each of printing rolls H and i2 additional eccentric bushings 95 and 91 are provided. These bushings need not be adjustable, however, and are illustrated as permanently secured in one position by screws 98. The shafts 42 and 92 could be journaled directly in the frame 43 in lieu of bushings 95 and 91, but the provision of the bushings 96 and 91 is more convenient and supports the shafts better. i

The amount of pressure between the blanket roll II and th plate roll I may be adjusted by turning the shaft 42. In other words, the same means is used for the throw-out as for the pressure adjustment. It will be observed that the pressure between these two rolls depends upon the position of the shaft (l2 at the time that the latch lever 56 is in its final position in engagement with the lug SI. This position may be adjusted by loosening screws Idi which extend through slots I02 in the latch lever t5 and screw into plate I03 having a hub I [it keyed to shaft 42. When latch lever 45 is in its latched position and the screws IIJI loosened, the handle it may be turned to adjust the pressure between blanket roll II and plate roll I 4, after which the screws IGI may be tightened. Thereafter, every time the latch lever G6 is moved to its final latching position, the same contact pressure will be obtained, assuming uniform. plate thickness on the plate roll I I. Of course, when the plate roll It is changed, readjustment of the pressure may be made very easily after loosening screws I8 I The eccentricity of shaft 42 (line B-D) is preferably normally disposed approximately parallel with a line C-E between the axes of platen I2 and plate roll it, so as to have a maximum component of motion away from these rolls during the first part of the throw-out.

The pressure of the platen against the blanket roll is similarly controlled. The shaft 92 is provided with eccentric bearing portions I05 similar to the eccentric bearing portion ll of shaft 52. It is about these eccentric portions I06 that the platen I2 rotatw. Likewise, the shaft 92 is preferably provided with a handle I01 so that the shaft 92 may be rotated to shift the eccentric portions I06 and hence the platen I2 toward or from the blanket roll II. When the proper adjustment of pressure is obtained, the adjustment may be secured by tightening screw I08 which extends through a slot in the base portion of handle I07. It will be observed that this adjustment is made with extreme eas and hence can be varied quite readily if changes in the thickness of the sheets should so require. Of course, this adjustment should be made when the latch lever 46 is in its final position and after the pressure between the blanket roll II and plate roll I 4 has been adjusted.

Inasmuch as these various adjustments move the rotational axes of the rolls toward and from one another, a problem is encountered in connection with the gearing of these rolls since gears are of course designed to be operated about axes an exact distance apart. If the gears are slightly separated, there will be excessive slack between them and if they are moved closer together there will be a tendency toward a binding effect between them. In either event, th friction and wear will be increased. According to the present invention the gears are maintained at constant axes regardless of movement of the printing rolls.

This means of course that the central axis of a given printing roll will not always coincide with the axis of the gear and it is necessary to provide some means for accommodation between these two axes. According to the present invention a'coupling is provided of the type known as an engagement with the blanket roll II in the perpendicular direction. This permits the blanket roll I I to have a planetary movement about the axis of the gear H2 as the two rotate together. The sliding relationship is accomplished by means of radial splines IM and IIS on the gear and roll respectively, which fit in corresponding grooves in the intermediate coupling member III. As gear H2, coupling I I! and roll II rotate they never depart from the constant angular relationship they would have if keyed to a single shaft.

In similar manner, an-intermediate coupling member III; is provided between the gear H9 and the platen I2, having the same engagement with each of these members as does the intermediate member III with the gear II 2 and the blanket roll II.

It may be observed that a single bushing I20, preferably of hardened steel, may be secured to the frame 43 to serve as a bearing for both the bushing and the gear H2 which may in turn have a sleeve of bearing metal for engaging the bushing I20. This positions the bushing 96 concentrically with the gear H2 so that, as seen best in Fig. 9, it is out of alinement with bushing 8%.

Control of counter It is common practice with printing presses to provide a counter for counting the sheets as they are printed and such a counter has been shown at I2I in Fig. 2. This counter is actuated by a counter lever I23 which is pivoted at I24 to the press frame 43. The counter lever I23 rides on cam I26 during operation of the press. The cam I26 rotates with the plate roll I4 andupon every revolution thereof the low part of the cam permits spring I2I to draw the counter lever I23 down and operate the counter I2I.

If the press continues to rotate after the blanket roll I I is thrown out, it is of course desirable that the counter should not operate since it would produce a false count. To prevent the counter from operating, the latch lever 46 is provided with a hook-like extension I28 which slips over a flange I29 on the idle end of the counter lever I23 thereby holding this counter lever in the position shown in Fig. 2 so that it cannot operate the counter I2I even when the low part of the cam I26 is adjacent the counter lever I23. The end of the hook I28 may be beveled so that even with the counter in the position shown in Fig. 3 the hook will pass over the flange I29 if the latch arm 52 should be operated at that time to cause a throw-out. However, the relationship of cam I26 and cam 33 is such that the automatic throw-out would never occur when the counter lever is in the position shown in Fig. 3.

It should be noted that hook I28 is sufllciently long so that the counter does not again come into operation until the latch lever is moved substantially to its final latched position, i. e. after it leaves the intermediate position.

Operation In preparing the press for use, the eccentric bushing 84- is first adjusted to provide uniform contact pressure along the line of contact between the blanket roll II and the plate roll I4. Next, the eccentric bushing 9| is adjusted to provide uniform contact pressure along the line of contact between the platen I2 and the blanket roll II. Of course, these adjustments should be made when the various rolls are approximately in their operative positions. Next, the proper pressure is obtained between the blanket roll II and the plate roll H by loosening the screws l! and turning the handle 44 while the latch lever 48 is locked in operative position by the latched lug The pressure of the platen it against the blanket roll ll may be adjusted by turning the shaft 92 after loosening screw I98.

To start the press for a given run or after a throw-out, it is merely necessary to turn .the handle 44 through two steps. In the first step the latch lever 46 latches on the lug 55. This initial movement actuates rod 58 to turn on the motor switch 51. When the desired speed has been reached, the handle 44 is turned farther to latch the latch lever 46 on lug 5|. This second movement brings the blanket roll ll into proper contact with the plate roll it and the platen I2 and also releases the counter lever I23 so that it will count the sheets that are printed. If at any time there is no sheet on the feed table 31 at the time the sheet should be fed to the printing rolls ii and It, the blanket roll ii may be thrown out, and separated from both the platen i2 and the plate roll it merely by lowering the latch arm 52 for which purpose the handle 56 thereon is provided. This permits spring 61 to snap the latch lever 56 against the stop t8, thus turning the shaft 52 so that the eccentric bearing portions Q! are moved to remove the blanket roll ll away from both of the other'rollsrThis throw-out movement of the lever 46 also causes the extension I28 to block further movement of the counter arm I23 and furthermore actuates I the rod 58 to operate the switch 51 to the off position, thus stopping the press.

If the automatic control features are provided, the feeler will be reciprocated once for each revolution of the blanket roll H. Normally this will have no eifect for the feeler l5 will rest on top of the sheet which is being fed. When no sheet is present, however, the feeler '55 will fall through the slot 13 and engage the lug E3 of release arm i2, thereby operating the latch arm 52 downwardly, thus producing the throw-out as described in connection with the manual operation.

From the foregoing it is seen that a printing press is provided having an extremely simple and satisfactory throw-out mechanism. No longitudinally sliding parts or guideways are required. Both the throw-out and the adjustment of the pressure of the blanket roll on the plate roll are accomplished by means of a shaft having eccentric bearing portions for the blanket roll. This same shaft is journaled eccentrically in a bearing bushing which can be rotated to, adjust the uniformity of pressure of the blanket roll on the plate roll. Similar means for adjustment of pressure and uniformity of pressure are provided for the platen. In each case the bearing bushings are journaled within a bearing member which also serves as a fixed bearing for the gear driving the adjacent roll. The possible displacement of the axis of the roll and of the gear is compensated for by an Oldham coupling.

The eccentric type of throw-out mechanism lends itself admirably to the provision of a simple type of latch which may easily be controlled automatically if desired. Furthermore, the latch mechanism is preferably coupled to the motor control switch and the latch is preferably provided with two steps so that a single handle may be used first to turn on the motor by movement to the first step and then to throw the printing rolls into contact by movement of the second stepi With this arrangement the operation of the throw-out will automatically turn off the motor. The mechanism may also be coupled to the counter so that it will also stop the operation of the counter.

Although the apparatus need not be designed for disposing the eccentrics at the angular positions shown in the drawings, these positions will give the most satisfactory directions of movement, even though in the case of the blanket roll II this requires two difierent directions of movement. Thus, the throw-out movement of the blanket roll should be in a direction which moves it substantially equally away from both the plate roll and the platen roll, while for the alining adjustment the movement of one end of the blanket roll should be directly toward and from the plate roll H. To provide the throw-out movement the apparatus is designed to place the axis B of stub shaft 83 in theposition shown in Fig. 9 with respect to the axis D of the blanket roll II. The initial movement of the center D as the shaft is rotated about the center B will be in a direction perpendicular to the line B--B. Hence, with this line parallel to the line 0-2: the initial movement will be approximately v equally away from both of the rolls. As a matter of fact, because of the larger size of the plate roll i6 the initial movement will produce a little less separation from this roll, but because of the circular movement of the axis D the latter part of the movement will be greater with respect to the roll it so that the total separation is still about the same from both rolls.

Since the eccentric St is moved only to adjust one end of the blanket roll it toward or from the plate roll it, it is desirable that this eccentric be so disposed that it will provide this movement with the least undesirable components in other directions. Hence, the eccentric bushing 84 is positioned with its axis A on a line extending through the axis B and perpendicular to the line 3-0. Any movement along this line will ordi-' narily be extremely small and hence the fact that the path of the axis B is circular is not significant. It will be observed that because the motion of the axis B is along the line BC this adjustment does not tilt the axis B out of its common plane with the axis C and, furthermore, it has almost ho effect on the uniformity of pressure between blanket roll it and platen roll it. It will be observed that if the bushing 98 were used for this adjustment, the direction which it would move the axis B would not be nearly as satisfactory because the bushing 96 is concentrically positioned with respect to the gear H2. Ordinarily such bushings as the bushings 96 and 84 would be positioned in alinement but by positioning them out of alinement and by adjusting the one which is independent of the gearing the advantageous direction of movement of the axis B, already discussed, is obtained. This misalinement of the bushings 8t and is thus an expedient adopted for the purpose of providing two different" directions of movement, namely the throw-out movement away from both the platen i2 and the plate roll it and the adjusting movement which is directly toward or away from the plate roll it. Although the bushings 84 and 96 are misalined when they are in the illustrated angular positions for which they are designed,

shaft 52 will be truly parallel with the axis of plate roll it.

In connection with the platen l 2 it is not necessary to resort to the misalinement of the bushings since only one direction of movement of the axis E is desired. This direction is toward or from the blanket roll ii and hence the rotational axis F of the shaft 92 is positioned on a line extending through the point E at approximately right angles to the line D--E. For convenience, since no other direction of movement is necessary, the bushings 9i and 9? are positioned concentrically with the gear H9 which is concentric with the normal position of the platen roll 52.

In using the terms engagement or contact herein with reference to the blanket and platen rolls ii and i2, it is of course not intended to imply that there is no sheet between them.

We claim:

1. An ofiset printing press including a plate roll, a blanket roll for receiving ink from the plate roll, a platen roll for pressing a sheet to be printed against the blanket roll, means for feeding successive sheets to the blanket roll to be printed; the blanket roll being movable in a direction away from both the plate roll and the platen roll so that it may be separated from both the platen roll and the plate roll by a single movement and being biased in said direction; latch means for latching the blanket roll in normal engagement with the plate roll and platen roll, means for automatically releasing the latch means, said means being ineffective if a sheet is being fed to the blanket roll at the proper time, and means for stopping the press when the blanket roll is thrown out.

2. A printing press including a printing roll rotatable on an eccentrioally mounted shaft, inkapplying means for applying ink to the printing roll, a platen roll for pressing a sheet to be printed against the printing roll, and means applied to one end of the shaft only for turning said shaft; the angular disposition of the shaft being such that as it is turned in the appropriate direction the printing roll initially moves in a direction away from both the ink-applying means and the platen 'roll.

3. A printing press including a printing roll rotatable on an eccentrically mounted shaft, inkapplying means for applying ink to the printing roll, a platen roll for pressing a sheet to be printed against the printing roll, means applied to one end of the shaft only for turning said shaft; the angular disposition of the shaft. during the printing engagement being such that an extended line between the shaft axis and eccentric center is remote from and outside of the points of contact between the printing rolls so that as v the shaft is turned in the appropriate direction the printing roll moves in a direction away from both the-ink-applying means and the platen roll, and latch means for securing the shaft at an angular position for holding the rolls in contact and releasable to let the shaft turn to move the rolls out of contact, said latch means including a fixed latch member and an arm for cooperating therewith secured to the shaft with angular adjustability whereby the pressure between the rolls can be predetermined by the angular adjustment of the arm on the shaft.

4. A printing press including a. printing roll rotatable on an eccentrically mounted shaft, inkapplying means for applying ink to the printing roll, a platen roll for pressing a sheet to be printed against the printing roll, means for turn- 75 ing said shaft; the angular disposition of the shaft being such that as it is turned in the appropriate direction the printing roll moves in a direction away from both theink-applying means and the platen roll, latch means for securing the shaft at an angular position for holding the rolls in contact and releasable to let the shaft turn to move the rolls out of contact, said latch means including a fixed latch member and an arm for cooperating therewith secured to the shaft with angular adiustability whereby the pressure between the rolls can be predetermined by the angular adjustment of the arm on the shaft, and a switch for controlling the rotation of the rolls connected to the arm to be operated thereby in the initial part of the movement of said arm in returning the movable roll to its operative position after a throw-out.

5. A printing press including two printing rolls, one of which is movable with respect to the other, a control member for moving the movable roll into contact with the other, and a motor switch for controlling the rotation of said rolls and operated to the "on position by the control memher before it moves the movable roll into contact with the other roll.

6. A printing press including two printing rolls, one of which is movable with respect to the other, throw-out means for causing the movement of the movable roll away from the other adapted to be manually reset, and a switch for controlling the rotation of .the rolls operated to the ofi position by a roll-separating operation of the throw-out means and to the on" position by a reset operation thereof.

'7. A printing press including a pair of rolls adapted to rotate in contact with one another, a shaft eccentrically journaled for carrying one of the rolls, means for turning the shaft and looking it in a turned position to adjust the contact pressure between the rolls, an eccentric bushing journaling the shaft at one end thereof and turnable to-adjust the uniformity of contact pressure along the line of contact between the rolls, said bushing with the shaft therein being carried on the inside of a fixed bearing member, a gear rotatably carried on the outside of said bearing member, and a variable-axis coupling connecting said gear and movable roll.

8. A printing press including a pair of rolls adapted to rotate in contact with one another, shaft means for carrying one of the rolls, a bearing for one end of the shaft means, and a pivotally mounted bushing having the other end of the shaft means eccentrically journaled therein, some point on the orbit of the center of the eccentrically journaled shaft end being in a line extending through the center of the other shaft end and substantially parallel with the axis of the other roll.

9. A printing press including a pair of rolls adapted to rotate in contact with one another, shaft means for carrying one of the rolls, a bearing for one end of the shaft means, and a pivotally mounted bushing having the other end of the shaft means eccentrically journaled therein, some point on the orbit of the center of the eccentrically journaled shaft end being in a line extending through the center of the other shaft end and substantially parallel with the axis of the other roll, this point being approximately at a point of tangency between said orbit and the line extending to said axis.

10. Aprinting press including two printing rolls, one of which is movable with respect to the other, throw-out means for causing the movement of the movable roll away from the other and including a control member for resetting the rolls, and a switch for controlling the rotation of the rolls operated to the off" position by operation of the throw-out means and operated to the on position by operation of the control member in its resettingmovement before it moves the movable roll into printing relation with the other roll.

11. A printing press including two printing rolls, one of which is movable with respect to the other, throw-out means for causing the movement of the movable roll away from the other and including a control member for resetting the rolls, and a switch for controlling the rotation of the lOlls operated to the off" position by operation of the throw-out means and operated to the "on position by operation of the control member in its resetting movement before it moves the movable roll into printing relation with the other roll, the throw-out means also including latch means for latching the control member in two operative positions, one corresponding to the position at which the switch is turned on, and the other corresponding to the position at which the rolls are in printing relationship.

12. A printing press including a blanket roll, a plate member and a platen member, with the blanket roll movable between two positions in one of which it engages the plate member and the platen member and in the other ofwhich it engages neither, and a control member operable to a position at which it causes operation of the press to cease, operable to a printing position for causing the movement of the blanket roll into printin engagement with the other two members and operable to a preliminary position, before causing the blanket roll to engage either of the other members, for causing the press to operate normally in respects other than engagement between the blanket roll and said members.

13. A printing press including a blanket roll, a plate member and a platen member, with the blanket roll movable between two positions in one of which it engages the plate member and the platen member and in the other of which it engages neither, a control member operable to a position at which it causes operation of the press to cease, operable to a printing position for causing the movement of the blanket roll into printlng engagement with the other two members and operable to a preliminary position, before causing the blanket roll to engage either ofthe other members, for causing the press to operate normally in respects other than engagement between the blanket roll and said members, and latchv means effective to hold said control member in either the preliminary position or the printing position.

14. In a printing press, a printing couple including a rotating cylinder, means for feeding sheets to the couple including registration stop means against which a sheet is preliminarily fed, feed rollers for advancing the sheet from the stop means to the printing couple, means for intermittently rotating one of said rollers in timed relation to the rotation of said cylinder, a sheet detector moved in the direction of movement of the sheet during the feeding movement of the driven feed roller adapted to be supported by the sheet if a sheet is present and adapted to drop through the intended plane of the sheet if the sheet is absent, and throw-out means controlled by the forward movement of the sheet detector if it has dropped through the intended plane of the sheet for separating the members of the printing couple. I

15. In a printing press, a printing couple including a. rotating cylinder, means for feeding sheets to the couple including registration stop means against which a sheet is preliminarily fed, feed rollers for advancing the sheet from the stop means to the printing couple, feed control means including cam means on the cylinder for moving one feed roller toward the other substantially without rotation of either feed roller and for thereafter driving one of the feed rollers to advance the sheet from the stop means to the printing couple, a sheet detector actuated by the same cam means and moved in the direction of movement of the sheet during the feeding movement of the driven feed roller adapted to be supported by the sheet if a sheet is present and adapted to drop through the intended plane of the sheet if the sheet is absent, and throw-out means controlled by the forward movement of the sheet detector if it has dropped through the intended plane of the sheet for separating the members of the printing couple.

16. In a printing press, a printing couple including a. rotatable cylinder, a shaft supporting the cylinder for rotation about the axis of the cylinder and eccentrically journaled for a pivotal movement moving the cylinder toward or from the other member of the printing couple, a control member carried by the shaft, and means for maintaining the 1 control member at a predetermined position to produce a predetermined pressure between the members of the printing couple; the control member being angularly adjustable on the shaft and securable in a predetermined position thereon by screw means extending through slot means in the control member and screwed home to draw the control member into rigid relationship with the shaft.

.17. In a printing press, a. printing couple ineluding a rotating cylinder, means for feeding sheets to the couple including registration stop means against which a sheet is preliminarily fed, feed rollers for advancing the sheet from the stop means to the printing couple, feed control means including cam means on the cylinder for moving one feed roller toward the other substantially without rotation of either feed roller and for thereafter driving one of the feed rollers to advance the sheet from the stop means to the printing couple, a sheet detector actuated by the same cam means and moved in the direction of movement of the sheet, adapted to be supported by the sheet if a sheet is present and adapted to drop through the intended plane of the sheet if the sheet is absent, and throw-out means controlled by the forward movement of the sheet detector if it has dropped through the intended plane of the sheet for separating the members of the printing couple.

.WILLIAM WARD DAVIDSON, JR.

EDWARD FRANK DELL.

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