FR2512743A1 - Sheet offset printer with electronic-pneumatic rectification - has microprocessor control from optical detectors with sheets constantly supported during rectification and margin setting - Google Patents

Abstract

The machine has pneumatic and electronic systems for rectification and margin setting. An arrangement of cylinders permits the transfer of fully finished printed sheets, by use of a pressure cylinder of doubled diameter. The cylinder has two arcs of a circle of 145 degrees on its circumference. A microprocessor with optical detectors commands and controls the pneumatic and electronic systems. The sheets are constantly pneumatically held during rectification and margin setting until complete closure of the pressure cylinder grips. In the occurrence of a defective rectification, the margin is interrupted by having the aspiration cut off at the margin cylinder - and the sheets in the process of being printed are completely printed. The sheet supply is interrupted and the sheets remain on their margin table.

Description

 The present invention relates to the modular construction of sheetfed offset machines with pneumatic and electronic correction and margin systems, as well as a special arrangement of the cylinders allowing the transfer of fully finished printing sheets.

 Pneumatic and electronic adjustments ensure perfect positioning of the sheets on the margin table.

The pneumatic margin of the sheets to the pressure cylinder with electronic control gives impeccable location even at very high speed. The sheets are constantly maintained tire matically, no risk of rebound of the sheet during corrections. The margin is continuous, without interruption in the flow of leaves,
The special arrangement of the cylinders, and the use of double diameter pressure cylinders, allows the transfer of fully finished print sheets.

 The result: no transfer of sheets during the printing phase, the sheets never take the form of an S during printing, the sheets are never pulled by the output clamps still under pressure and stretched by discs or segments.

 Main advantages: Elimination of the winding of the sheets when printing heavy shapes, the sheets remain flat, elimination of the risk of zones, of doubling S no more locating defect at the end of pressure, more marks caused by discs or segments , reduced risk of paper stretching, improved sheet output on reception, fewer adjustments, faster registration.

 Double diameter pressure cylinders make it easier to print heavyweight paper. Each rotation of the pressure cylinder fitted with two gripper bars corresponds to two prints, which allows greater speed.

 The special arrangement of the cylinders allows the modular construction of multi-color or convertible machines for double-sided printing; all the solutions being possible by the use of transfer elements convertible or not between the printing groups.

 The printing units are absolutely identical, the small recess on the plate and blanket cylinders allows an almost uninterrupted ink film. Printing of one color is complete before printing of the next color. The path of the sheets between each group is identical and long enough to allow good ink absorption on the paper before printing the next color; this results in a logical sequence of multi-color printing.

Arrangement of cylinders - Plate 1
The pressure cylinders C, the output drums S, the transfer cylinders T, and the margin cylinders M have a double diameter than those of the plate cylinders P and of the blanket cylinders B.

 Printing unit: Relative to the axis of the pressure cylinder C, and along a vertical plane and from axis to axis, the blanket cylinder is offset by 250 on the left and upwards, relative to the cylinder blanket holder B, the plate cylinder P is offset by 100 on the right and upwards. Relative to the pressure cylinder C, the outlet drum S is offset by 10D to the left and down.

 Transfer element: The transfer cylinder T is on the same horizontal plane as the output drum S of the printing unit. the axis of the margin cylinder M is offset by 500 to the left and upwards, relative to the axis of the transfer cylinder T.

 The pressure cylinder C has on its circumference two arcs of circle of 1450, these arcs of circle correspond to the maximum development of the impression. The two arcs of circle of 350 correspond to the hollow of the cylinder where the gripper bars are housed. The large arrows indicate the direction of rotation of the cylinders.

 The plate and blanket cylinders have an arc of 2900 for the printing circumference and 700 for the hollow allowing the plate and the blanket to be attached.

 Plate 2 presents a feeder element and a printing unit.

 Feeder element 4 The sheet feed is provided by a conventional sheet feeder with suction head T comprising lifting suction cups and transport suction cups. Deselectors D are placed on the margin stack. The margin works covered, with X cords and rollers. In K are the pneumatic and electronic correction and margin systems, the description of which is given elsewhere.

 Printing unit: E film inking block with anti-carry system on the last touch roller and zone adjustment (to be the subject of a certificate of addition).

M mooring block with R refrigeration system and zone adjustment (subject to a certificate of addition).

F automatic washes of inking and wetting (separate washes). G automatic blanket washing. C adjustment of the circumferential marking with graduated scale of the plate cylinder. The setting of the lateral marking with graduated scale of the plate cylinder. P pressure adjustment with comparator and graduated scale, H Plate pre-registration system (must be the subject of a certificate of addition)
Q protection bar between the plate cylinder and the blanket cylinder acting as a stop (emergency stop).

 The small arrows around the pressure cylinder and the outlet drum indicate blowers and an air cushion outlet (to be the subject of a certificate of addition).

 Plate 3 presents two printing units and a convertible transfer element. The transfer element has two cylinders, the transfer cylinder and the margin cylinder.

Two types of transfer elements are provided: transfer element for multi-color printing. The output drum of the first printing unit transmits the sheet to the transfer cylinder, which forwards it to the margin cylinder, which places it in the pressure cylinder of the next printing group.

Convertible transfer element, sheet grip from the rear. The transfer cylinder is then equipped with a conversion system W with graduated scale (adjustment according to the format of the sheets) which synchronizes the assembly for double-sided printing,
It is also equipped with Y suction lollipops which hold the sheets stretched from behind,
The margin cylinder is equipped with special clamps which pivot from 1800 to take the sheets from the rear, position B, and which gradually return to position A to feed the sheet. The position of the sheet when turning over for double-sided printing is indicated by dotted lines V, a blower then holds the sheet during the ascent. (The entire turning system will be subject to an addition certificate).

 Plate 4 presents a printing unit and a high stack output element. On the last printing unit, the output drum is not equipped with gripper bars, it serves as a guide for the conveyor chains; the conveyor rise angle is only 370, thus avoiding any deformation to the paper. The transporter has eight clamp bars.

 The output element is equipped with an automatic non-stop reception N (which must be the subject of an addition certificate).

Rotary blowers H, de-electrifiers D, a powder
Z with antistatic system.

 Plate 5 presents a printing group with output.

low battery. The output drum of the printing unit is in this case one third smaller than the pressure cylinder, and it is offset by 200 to the right and downward with respect to this same pressure cylinder.

 This output can also equip multi-color machines. The position of the other cylinders remains unchanged.

 The low stack reception offers the possibility of having a typographic element A for numbering, punching, slitting, creasing, or printing a spot color. Above cylinder A the inking system with automatic washing.

 Plate 6 presents a one-color machine with low pile reception, with automatic non-stop reception N, blower bars, H, powder Z, deselecters D, anti-static system J, The conveyor comprises four gripper bars.

In A cylinder of the typographic element.

 The typographic element can be uncoupled for lm offset printing only.

 Adjustments and pneumatic margin, the whole is fully controlled and controlled electronically. The sheets are constantly held pneumatically during the frontal and lateral rectifications, as well as during the margin, until the pliers of the pressure cylinder are completely closed.

 This principle implies a margin absolutely parallel to the axis of the pressure cylinder. This is fitted with fixed margin stops. The front stops, also fixed, are in perfect alignment with the stops of the pressure cylinder, but 1 mm in advance. This advance causes perfect contact of the sheet with the stops of the pressure cylinder. In contact with the sheet with these stops, optical detectors control a suction in the gripper grip (1 cm) of the pressure cylinder, the sheet is therefore in perfect contact with the stops and is held pneumatically on the pressure cylinder before and during the clamps are completely closed, then the suction is cut off.

This gives very high accuracy in registration, even at very high printing speed.

All operations are controlled by a microprocessor, connected to optical detectors (HEDS 100 HEWLETT
PACKARD) pulses of 700 ss s, frequency t kHz and to a main control cell, mounted at the front of the margin table.

 The set of adjustments and margins is composed of the following elements: plate 13 - Downstream of the power cords Xs two optical detectors A check the parallelism of the sheets, and indicate to the microprocessor a possible shortcoming which will be corrected by the two suction cylinders B, according to the correction orders transmitted by the microprocessor. the rotation of these cylinders is controlled by two motors with electronic speed variator. They also ensure the arrival of the sheets at the front cleats, reducing their speed at the end of the journey, thus allowing a front rectification in slow motion. V lateral rectification block comprising different parts, the detailed description of which is indicated elsewhere. Q plates closing the hollow in the margin table allowing the lateral rectification block to pass during format changes.

 Pneumatic margin cylinder I - suction pads F placed in front of the front tabs C - hollow C1 in the margin table allowing the passage of the front tabs during their pivoting - rollers J lifting the sheets after the margin and thus authorizing the rectification of the sheet next - optical detectors D checking the correct alignment of the sheet after the front rectification - main cell controlling all the rectifications and the printing process. E.

 During a faulty rectification, the margin is interrupted (the suction is cut off at the margin cylinder), the sheets being printed are completely printed, the sheet feed is interrupted, the sheets remain on the margin table . The cylinders are depressurized: The ink supply is interrupted, the ink rollers are raised, the machine speed returns to the starting speed. Therefore impossibility of poorly fed sheets, no risk of deterioration of the blanket.

Pneumatic and electronic lateral rectification blocks V (one on the right and one on the left)
Plate 12 shows the left lateral rectification block (the right lateral rectification block is inverted with respect to that on the left).

 Figure 11: section of the lateral rectification block.

Figure 12: top view of the same block
Figure 13: position of the optical detectors
A lateral rectification block comprises the following parts: two optical detectors - upper H1 - and
H2 lower - offset by 2 mm (figure 13)
A plate S on which is mounted a small guide roller Y facilitating the passage of the sheet under the plate. A suction plate G animated with a lateral movement from right to left, or from left to right depending on the rectification block.

 The block is mounted on an axis T and slides on this axis for positioning according to the paper size; this is achieved by unlocking the screw K. The block is parallelized by guides provided with bearings placed under the table.

R (figure 11)
Precise positioning is ensured by a millimeter ruler placed in the margin table in correspondence with the feeder stack. An arrow indicates the exact position of the optical detector H2. (figure 12). A micrometric adjustment, adjustable in operation is possible with the U softness with graduated scale. (figure 11).

 The removal of the caster from the classic pulling cleat eliminates the risk of marks by this caster. The absence of a stop at the cleat allows precise location, even in the case of poorly balanced sheets, the stop being replaced by the two optical detectors H1 upper for pre-rectification and H2 lower for rectification and control. More adjustment of the roller pressure, faster setting, more risk of rebound of the sheet on the stop.

 Decomposition of the front and side adjustments, as well as the margin (plates 7 - 8 - 9 - 10 and it).

Plate 7 - Figure 1 - The sheet supplied by the cords X is checked by the optical detectors A, it is then taken in charge by the suction cylinders B which pre-rectifies the sheet (as indicated on page 5). Figure 2 - The sheet slowed down by the suction cylinders B arrives at the fron rate cleats C, the alignment is controlled by the optical detectors
D, suction starts at the pads F. The rollers J retract under the margin table. At this instant the sheet is held by the cylinders B and the pads F. This is the start of the frontal grinding. Figure 3 - Frontal grinding - The suction is cut at the cylinders B, the sheet is held by the plates F, coupled with the front cleats which arrive at their top dead center. The precision of the rectification is always checked by the optical detectors D. The suction is then given to the suction plate G of the lateral rectification block. At this instant the sheet is held by the plates F and G. The frontal rectification is finished.

 Plate 8 - Figure 4 - then begins the lateral correction. The suction is cut off at the pads F. The sheet being held by the pad G.

Lateral grinding - lateral movement broken down from Figure 4 (plate 8) into plates 10 and 11 - Figures 9 and 10
Figure 9 - The sheet Z is held pneumatically by the plate G which is driven in a lateral movement to the left (pneumatically controlled movement), the sheet arrives under the optical detector H1 which signals its passage to the microprocessor. This instructs to give the suction to the margin cylinder when stopped, and to cut the suction to the G plate 2 mm further. The margin cylinder also begins a lateral movement to the left of 2 mm. In the case of right lateral rectification, the movements are reversed.

Figure 10 - The sheet Z arrives at the optical detector H2, which controls the rectification, the suction is cut off at the plate G, the sheet is held by the margin cylinder
The lateral correction is finished.

 The margin process begins.

 Plate 8 - Figure 5 - The sheet is held by the margin cylinder I which begins its rotary movement. the front tabs retract under the margin table. The rollers J start their upward movement, while by the plates F a blower lifts the sheet from the margin table. Figure 6 - The continuous margin and next sheet The approach of optical detectors A.

 Plate 9 - Figure 7 - The sheet is aligned on the stops N of the pressure cylinder, the alignment is controlled by optical detectors placed in the clamp grip of the cylinder in perfect alignment with the stops N. A suction 0 also placed in gripping the cylinder clamps securely holds the sheet before the clamps are completely closed, and this in precise location. The rollers J are at their highest point, thus allowing the next sheet to continue its advance, helped in this by the blower of the pads F. The rollers M guiding the sheet in the clamps of the cylinder. Figure 8 - the sheet being correctly fed and in precise location, the suction is cut at the margin cylinder, the clamps P are closed, the blower of the pads F continues to lift the fed sheet, allowing the passage of the next sheet. The tabs begin their upward movement for the next adjustment. The margin process is complete.

Claims (3)

KEVENDICATIONS  1. Offset machines, modular construction sheets, from one to several colors, the latter being convertible or not into double-sided printing, characterized by pneumatic and electronic correction and margin systems, as well as by a special arrangement of the cylinders allowing the transfer of sheets printing completely finished.  2. Sheet-fed offset machines according to claim 1, characterized by pneumatic and electronic correction and margin systems controlled and controlled by a microprocessor connected to optical detectors. The sheets being constantly held pneumatically during the adjustments and the margin, until the pliers of the pressure cylinder are completely closed.  3. Modular sheet offset printing machines according to claim 1, characterized by the special arrangement of the cylinders. The pressure cylinder being of double diameter and having on its circumference two arcs of a circle of 1450, corresponding to the maximum development of the printing and thus allowing the transfer of the fully finished printing sheets.