Printing unit within a rotary offset sheet printing machine

The present invention relates to a printing unit within a rotary offset sheet printing machine.

More specifically, the invention relates to such a machine also comprising devices for enumeration, overprinting, perforation and cutting of the sheets, during and after regular monocolor or multicolor printing on printing machines of the above type.

As a matter of fact, these operations, which are complemental to the very printing, are for example required in the occurrence of sequential enumeration of different documents, for example current account cheques, travel documents (such as tramway tickets, theatre tickets, sport meeting tickets and the like), documents which inter alia provide the proof of tax obligations, and anyhow in the preparation of other equivalent documentations, on printed forms.

Known offset sheet printing machines, including means for sequentially performing enumeration, overprinting, perforation and cutting of sheets or fractional sheets, can be encompassed in practice in the following three types:

• Type 1 - in which these operations are carried out by means of approaching, engaging and securing to the properly arranged printing machine, of an enumerating unit, adapted to perform other functions;
• Type 2 - in which the above operations are carried out by means of introducing and engaging, between shoulders of a properly arranged printing machine, of an enumerator bearing shaft, which can be drawn out and which can be connected in a releasable manner with supporting and controlling members secured in a stationary manner in the machine frame, and of an inking subassembly, which in its turn is adapted to be drawn out and which is connected in a releasable manner with the supporting and controlling members, arranged in a stationary manner in the frame of the same machine;
• Type 3 - in which the above operations are carried out by means of introducing and engaging, between the shoulders of a suitable arranged printing machine, of an operative subassembly provided with a related inking group and secured to one of the two machine shoulders, in such a manner that it can be pivoted about a vertical axis embodied by a shaft or a shaft portion or pivots arranged in a stationary position on the machine on one of the two shoulders.

Machines pertaining to the second one of the above types, and which are pertinent with the invention, have been described and illustrated in DE-A-22 21 343.

Briefly considering the prior art, it can be assumed that the first one of this three types of devices, associated to an offset printing machine, is subject to the drawback of requiring a remarkable space for applying to the machine the enumerating subassembly and for its storing and saving when the same device is not active, and also of requiring rather complicated operations for its transportation, detaching from or assembling to the machine, anytime the work is to be modified.

The second of the above types requires, additionally to the availability of space for the storing of the enumerator bearing shaft and of the related inking system during inactivity, the availabiity also of a work bench and of equipped stands for the preparation and the performance of the individual operations and for the storage of the individual components or component groups removed from the machine.

This second type is also subject to the drawback of its limitation to small formats, because of the weight and of the overall dimensions of said components or component groups to be handled anytime the work is to be modified.

In the third type of said devices, at last, the overhanging supported weights which are arranged upon hinge means on one only of the machine shoulders, when the regular printing at highest speed is performed, can negatively and harmfully influence the quality and the precision of the print, additionally to limit the use to small formats.

From DE-B-2 223 686 there is known a removable printing unit within a rotary offset printing machine comprising its own printing unit and a main gear wheel fastened to the impression cylinder of the printing machine, the whole printing unit being mounted on a subassembly structure with side frames which is slideably supported on guide means fastened to the side frames of the printing machine to slide the printing unit in and out of an operative position.

The subassembly structure can be withdrawn from the printing machine onto a transport carriage which is provided with rails which can be fastened to the guide means of the machine so that the whole printing unit can be transferred from the machine to the carriage and vice versa. The purpose of this known arrangement is however that of facilitating manipulation of the printing unit outside of the printing machine even when the unit is very heavy.

Therefore, the invention sets out to provide a printing unit within a rotary offset sheet printing machine, for one or several colors printing on medium or large format, allowing the alternate use of the machine as a regular one or as a several colors printing machine, or respectively as a "printing - enumerating - perforating - cutting" machine, without being subject to the drawbacks which are typical of the already known machines, and without requiring that components or groups of components of the unit capable of performing enumeration and other operations indicated above, and of the inking unit be carried externally of the machine, by means of operations which are simple and safely performable by one person, in particular by one printer employed for the machine.

To achieve this aim there is provided, according to the invention, a printing unit of the type known from DE-B-2 223 686, characterised in that the subassembly structure contains, in addition to the printing and enumerating unit, perforating and cutting devices, and is provided with an indexing means by which the meshing of the main gear wheel and the driving gear wheel is only possible in a predeterminated phase position of the enumerating shaft in relation to the phase position of the impression cylinder.

These and other more specific features of the invention will become evident from the following detailed description, referred to the accompanying drawings.

Anyhow, considering in advance and on the whole the improvement of this invention, this improvement allows to industrially carry out and associate to a printing machine an enumerating, overprinting, perforating and cutting subassembly which comprises itself any provisions required for its operation, including inking of the enumerating and overprinting means and means for ensuring correct phase position of the enumerating shaft in relation to the phase position of the impression cylinder. The subassembly is further:

• (i) simple and compact;
• (ii) permanently arranged between the side frames of the machine also when the same is used as a regular offset sheet printing machine, and when preparation of the work is performed;
• (iii) shiftable as a drawer on guide means secured in the inside of the side frames of the same printing machine, and
• (iv) disassociable for regular printing, for preparation of the printing with enumerating and so on, and for cleaning and maintenance of the same subassembly and of the same printing machine, by means of simple shifting of the "drawer".

Therefore, by operating according to the invention,

(v) when the machine is to be used as a conventional printing machine, or the preparation of a new work is desired to be performed, or cleaning or regular maintenance operations are to be made, it is enough, upon stopping of the machine, to shift the subassembly in its disengaged position (this position being preferably defined by the lighting of a warning light, green for example) and which corresponds to that of the complete retraction of the subassembly to a stroke end position, this position ensuring

• a) - disactivation of the enumerating etc. subassembly,
• b) - accessibility, of the printing machine components, and of those of the same subassembly, in particular of the rubber and impression cylinders, and of the components related to the outlet of the printed sheets;

(vi) - when, on the contrary, the typical enumeration, overprinting etc. operations are to be performed, upon stopping of the machine and having provided to the phasing of the actuating means of the subassembly with the actuating means of the machine, it is enough to shift the subassembly in the operative position (this position being preferably defined by the lighting of a for example red warning light).

In the embodiment described below and illustrated in the accompanying drawings, a machine in particular for "not large" formats will be considered, and parts thereof will not be detailedly described and illustrated as the several servocontrol means, automatic means, electronic synchronization means, as well as the several electrical, pneumatic, hydraulic, hydropneumatic, electronic and the like driving means are currently known for large format sheet printing machines, to which the invention can quite be applied.

In the enclosed drawings:

• Fig. 1 diagrammatically illustrates as a whole and in side view, a medium format single color offset printing machine having a printing unit according to the invention;
• Fig. 2 illustrates, in side view and in larger scale and detail, the components which control the subassembly and the elements located inside the same subassembly in the operative position;
• Fig. 3 illustrates a section according to sectional planes indicated at 3-3-3-3 in Fig. 2, showing the side frames of the machine, the impression cylinder and the subassembly including its principal elements, as well as the outside and inside elements which control the same subassembly, in the operative position thereof;
• Fig. 4 illustrates the means for phasing of the actuation means for the subassembly with the actuation means of the machine;
• Fig. 5 illustrates in sectional view and in diagrammatical manner, the side frames of the subassembly and the shaft which bears the enumerating unit;
• Fig. 5A is a sectional and elevational view of the detail of Fig. 5;
• Fig. 6 illustrates details of the means for displacing the enumerating unit with respect to the impression cylinder and of other characteristic mechanisms of the invention, during printing with enumeration, and
• Fig. 7 illustrates in elevational and sectional view, the subassembly including the inking unit for the enumerating and overprinting unit and anyway for the means related to the invention and requiring inking.

More particularly, referring to the figures of the drawings, a rotary offset sheet printing machine as illustrated in Fig. 1 comprises a sheet feeder assembly 10 and (in the example) an individual printing unit 12, a plate cylinder 14, a rubber roller 16, an impression cylinder 18, a shaft 20 for the outlet of the sheets, while the other components and elements typical of and known in printing machines of the type considered are omitted for simplicity sake.

Below the impression cylinder 18 and aside the sheet outlet shaft 20, there is arranged a subassembly structure comprising a printing unit and generally indicated at 22 in its operative position and at 22a (by a dot-outline) in its inoperative position.

This subassembly is slideably supported on suitably shaped guide means (not illustrated in the drawings) fastened to side frames 24 and 26 of the printing machine (see, for example, Fig. 3) to slide the printing unit in and out of an operative position.

Signalling means are provided for indication whether the printing unit is shifted into or out of its operative position. The signalling means may comprise lights of contrasting colours.

In the space circumscribed within the subassembly there is arranged a printing unit comprising a bearing shaft 28 of an enumerating unit, an inking roller 30, a milling roller 32, and various rollers which cooperate with the inking roller of the enumerating unit, that is an intermediate roller 34, a transfer roller 36, an ink fountain duct roller 38, and an ink fountain 40, these components and their cooperation being seen best in Fig. 2.

Practically, in the embodiment shown in the drawings, the subassembly is partially circumscribed by a chain 42 which carries the printed sheets to the outlet. The enumerating unit bearing shaft 28, and more precisely the very enumerating means (see below) cooperate in a known manner with the impression cylinder 18.

The driving means for the subassembly are at least partially illustrated in Figs. 2 and 3. All operative components included in the subassembly are actuated by a main gear wheel 44, which pertains to the same subassembly and which is supported outside of side frames 46 and 48 of the subassembly on the enumerating unit bearing shaft 28. The outline of the subassembly is indicated in Figs. 1 and 2.

In Fig. 3 there are also fragmentarily indicated at 50 the enumerating unit and perforating and cutting devices of the subassembly structure, and in the same Fig. 3 there is also illustrated the impression cylinder 18 and its related gear wheel 52. This gear wheel 52 is coaxial with and rotatably rigid with a driving gear wheel 54 which can be meshed at 56 with the main gear sheel 44 which actuates the devices comprised in the subassembly, i.e. an intermediate gear wheel 58 for the actuation of the inking unit, and a gear wheel 60 arranged on the main milling roller 32 of the same inking unit. In Fig. 3 there are also best seen the transfer roller 36, the intermediate roller 34, the fountain duct roller 38 and the ink fountain 40, having securing screws 62, 64.

The drive is indirectly transmitted to the fountain duct roller 38 by means of a ratchet gear 66 diagrammatically indicated in Fig. 3.

The remaining above described rollers of the inking unit (transfer, intermediate and inking rollers) are frictionally rotated by the rollers which are driven by the above indicated gear wheels.

The details of the driving of the individual rollers of the inking unit of the enumerating unit can be understood by the drawings and their specific description can therefore be omitted.

For the phasing operation between the driving gear wheel 54, fastened to the impression cylinder 18, and the main gear wheel 44, a phase control is provided comprising indexing means which will be described hereinafter. For indicating the respective phase positions of the gear wheels 44, 54, there are provided indication means which can be seen through an inspection opening 68 provided in the side frame 24 of the machine (Fig. 3).

The indexing means, by which the meshing of the main gear wheel 44 and the driving gear wheel 54 is only possible in a predetermined phase position of the enumerating shaft 28 in relation to the phase position of the impression cylinder 18, are best shown in Fig. 4, wherein said means are fragmentarily illustrated and evidenced.

The driving gear wheel 54 comprises a sector plate 70 having a sole recess 72, while the main gear wheel 44 (fragmentarily illustrated also) bears a congruent link embodied by a sole tooth 74, borne by a disk 74a which is connected to the main gear wheel 44 of the printing unit, and insertable into the corresponding recess 72 within the sector plate 70.

The outside of sector plate 70 and/or disk 74a comprising the sole tooth 74 is machined at a diameter which is some millimeters lower than the shallow recess of the gear wheels 44 and 54. The module of the sole tooth 74 and the congruent sole recess 72 is at least twice of that of the gearing of said gear wheels 44 and 54.

Further details of the subassembly structure are illustrated partially in elevational view and partially in sectional view in Figs. 5 and 5A. The dot-and-dash line 76-18 indicates the trace of the impression cylinder 18 (and therefore the sheet being printed) on which the enumerating unit 50 and the other devices operate.

On the enumerating unit bearing shaft 28 there are keyed at 28a, supports (which are at their turn enumerating unit bearings) consisting of two counterposed components 78' and 78", secured for example by means of bolts 80. The shaft 28 is supported in the side frames 46 and 48 of the subassembly structure by means of eccentric bushes 82' and 82" which are rotatably arranged for movements towards or away from the impression cylinder 18 in phased relationship, so that the enumerating unit can be approached or withdrawn according to a sheet present to be printed on. On said supports 78' and 78" there are secured eccentric disks 84' and 84" of horseshoe configuration, which concurrently hold the sheet pressed against the impression cylinder 18 when the enumerating and other operations are carried out.

As illustrated in Fig. 6, the device provided for applying and removing pressure upon the enumerating unit and the other operative mechanisms which are associated to the subassembly operates about the enumerating unit bearing shaft 28. The circle 76, indicated in dot-and-dash line, corresonds to the position of the enumerating unit when operating, and its arc 76a, which is eccentric relatively to said circle 76, defines the position of the enumerating unit and of the devices associated thereto in the un- pressed condition.

An arrangement including levers, tie rods, articulations and pivots 86, 88, 90 and 92 respectively, arranged for pivotal movement about a pivot 94, secured on the side frames of the subassembly, and a pneumatic or hydraulic cylinder 96, atuomatically operate when the feeding of the sheet to the impression cylinder is missing, and, upon a manual actuation, when it is considered necessary by the operator. Said components promote the rotation of the eccentric bushes 82' and 82" provided with a short lever 98, with consequent alternative pressing and respectively unpressing of the enumerating unit and other devices, arranging them in the position indicated at 76 or 76a.

The subassembly including the enumerating unit inking arrangement and possibly other devices which require inking and which are comprised in the subassembly, is detailedly illustrated in Fig. 7, in which there appears at least partially the path 76 of the enumerating unit about the related enumerating unit bearing shaft, a path which is tangent to the impression cylinder when the enumerating unit is in its operative overprinting condition.

The main inking roller 30 cooperates with the main milling roller 32 which in its turn cooperates with the adjacent intermediate roller 34. The roller 36 which acts as a transfer roller, is supported by a lever 100 which is journaled about a pivot 102, so that the transfer roller 36 can oscillate between the intermediate roller 34 and the fountain duct roller 38, which is rotated in the ink fountain 40, provided with a known doctoring and metering blade 104, which is adjustable by acting on set screws 106.

For adjusting the line pressure, the inking roller 30 is supported, by means of an eccentric pivot 108, by a lever 110, which is pivotable about an axis 112 coincident with the axis of the milling roller 32 which coacts with the inking roller 30.

The fountain duct roller 38 which is actuated by means of the ratchet gear 66 (which has been cited above and is diagrammatically shown in Fig. 3), and the oscillating lever 100, which is actuated by an actuating cam 116 by interposition of a small roller 114 supported by the same lever 100, integrate the arrangement for alternative forward and rearward displacement of the means for performing inking concurrently with the other movements.

The device also comprises means for adjusting inking. Such adjustment is made by means of the set screws 106, which operate on the blade 104 of the ink fountain 40.

A return spring 118 abutting on an adjustment bush 120, provides for obtaining a controlled action between the small roller 114 and the cam 116.

A rod 122, which threadably engages a small block 124 (which cooperates as an articulation with the end of the lever 110 opposite to the axis 112) provides for defining the position of the lever 110 of the inking roller 30, with consequent adjustment of the pressure of the inking roller 30 on the enumerating unit. A set screw 126 arranged upon the pivotable lever 100 discontinues the operation of the transfer roller 36.

By acting upon the bush 120, the load of the spring 118 can be adjusted. By taking advantage of the eccentricity of the pivot 108 of the inking roller 30 it is possible to ensure the parallelism between the axis of the inking roller 30 and the axis of the form bearing shaft 28 of the enumerating unit.