CN1004263B

CN1004263B - Inking and wiping method and device for ink roller printing machine

Info

Publication number: CN1004263B
Application number: CN85108460.5A
Authority: CN
Inventors: 飞田常司
Original assignee: Daiichi Machinery Service Co Ltd
Current assignee: Daiichi Mecha Tech Corp
Priority date: 1984-10-04
Filing date: 1985-10-03
Publication date: 1989-05-24
Also published as: CN85108460A; EP0178112A2; KR910000576B1; JPS6186264A; SG75790G; KR860003107A; EP0178112A3; JPH038265B2; EP0178112B1; ATE49535T1; DE3575393D1

Abstract

A component of an ink pad printing machine that makes the printing plate in the ink tank inked and scraped. The printing plate and the doctor blade are installed in the ink tank so that the two can rotate relative to each other step by step in one direction or in a reciprocating manner. , scrape ink on the printing plate. In the first case, the squeegee blade defines a closed area where the pattern to be printed can be placed; in the second case, two squeegee blades are provided, which are respectively in contact with the printing plate according to the direction of reciprocating rotation. Ink tank caps are installed to minimize volatilization of ink components and prevent contamination. The cover is closed except for the orifice where the printing ink pad contacts the printing plate, and the ink in the ink tank covers the printing plate, and no special ink filling process is required.

Description

Inking and wiping method and device for pad printing machine

The present invention relates to a method and apparatus for inking and doctoring printing plates used on intaglio pad printing machines, such as those widely known as pad printing machines (Tampoprint). More particularly, the invention relates to a method and apparatus in which printing ink is applied to a pattern provided on a printing plate which is doctored by a suitable doctoring blade, and printing ink is then drawn from the recesses of the printing plate by means of an ink pad provided as a component of the printing press.

In known pad printing machines, a printing plate having a pattern or pattern etched thereon is typically mounted in a bath and a doctor blade is arranged to scrape excess ink from the surface of the printing plate to leave ink in the recesses of the printing plate.

There are generally two types of prior art devices. One of the ink channels is fixed and a doctor blade or the like is arranged to move horizontally over the surface of the printing plate. In another type, the doctor blade or the like is fixed and the gutter is moved horizontally under the blade. These devices require an open ink reservoir so that the diluent or other components of the ink are volatilized over a period of time. The ink must be appropriately replenished if the printing is to be carried out continuously for a period of time, for example by means of an automatic diluent addition device. And the impurities can easily fall into the ink tank to contaminate the ink.

In an attempt to overcome the disadvantages of an open gutter, there has been a proposal to contain the ink in a tank facing the printing plate and having apertures in the area where the ink can be applied to the printing plate. However, this device still requires a printing plate with a high degree of flatness and is therefore suitable primarily for printing plates with a small printing portion.

A further problem with the known apparatus is that both wiping and refilling of the printing plate are necessary during each print cycle, which makes it difficult to perform continuous printing at a relatively high speed.

European patent application EP- ｃA-0012934 discloses ｃA method and apparatus for intermittently delivering ink material to an ink pad printer. Since the printing plate is of a cylinder type, both end surfaces of the cylinder are also contaminated with ink, and it is very troublesome to wash the ink on the end surfaces when the printing plate cylinder is replaced. Furthermore, the pattern drawn from the surface of the plate cylinder by the ink pad is transferred to the flat printed product in a pattern-wise manner. In addition, each time the pad is lowered onto the plate, the gutter cover is opened once, causing the ink diluent to evaporate.

It is a principal object of the present invention to at least reduce some of the problems discussed above with known inking and doctoring methods and apparatus for pad printers.

According to one aspect of the present invention there is provided a method of inking and doctoring a pad-printing press, in which ink is applied to a pattern provided on a printing plate which is doctored and ink is drawn from recesses in the printing plate by means of a doctor blade provided as a component of the press, the method being characterised by periodic operation of two steps, the first step being the relative rotation of the printing plate and a doctor blade to effect doctoring of the printing plate, and the second step being the use of the printing press to draw ink from the printing plate by means of the doctor blade while the doctor blade is in a stationary condition.

The relative rotation between the printing plate and the doctor blade can be performed either stepwise, always in the same direction, or in a back and forth manner. In both cases, the doctor blade may remain stationary while the printing plate rotates or the printing plate may remain stationary while the doctor blade rotates in a back and forth manner.

An advantage of the method of the invention is that it is no longer necessary to replenish the ink each print cycle by using a separately movable inking device. This allows the method to be carried out at a higher speed. In addition, the printing plate can have more than one printing part with continuous ink scraping, so that the printing operation can be carried out at high speed.

According to another aspect of the present invention there is provided an inking and doctoring apparatus for an ink pad printing press, the apparatus comprising a reservoir containing a printing plate and a doctor blade arranged to scrape ink off of an upper surface of the printing plate, characterised by a drive arrangement adapted to effect relative rotation between the printing plate and the doctor blade to effect doctoring of the printing plate, and by a reservoir cover arranged above the reservoir to minimise evaporation of ink components.

In such a device, the inked portion of the gutter remains almost completely sealed, leaving only the cylindrical doctor blade holder mounted through the gutter cover with an opening sufficient to lower a printing pad to suck ink up onto the design to be printed, thus largely preventing evaporation of ink (such as diluent). In addition, the possibility of impurities falling into the ink is also greatly reduced.

In the case where the relative rotation is stepwise and in the same direction, it is preferred that the doctor blade be configured to define a closed portion (such as a circular portion) in which a design to be printed on the plate can be located, the doctor blade only applying the ink when that design moves under the blade. Alternatively, where the relative rotation is in a back and forth manner, two doctor blades may be provided, arranged to alternately contact the printing plate, all depending on the direction of relative rotation between the doctor blades and the printing plate.

Brief description of the drawingsthe accompanying drawings:

FIG. 1 is a side view of a universal inking/doctoring apparatus for a printing press;

FIG. 2 is a side view showing an ink tank and a printing plate configured in accordance with the prior art;

FIGS. 3 (a) and 3 (b) are schematic illustrations generally representing an apparatus according to the present invention;

FIGS. 4 (a) and 4 (b) are schematic illustrations of an ink die and a printing plate configured in accordance with an embodiment of the present invention;

FIGS. 5 (a) and 5 (b) illustrate a cylindrical doctor blade holder for use in the apparatus of FIG. 4;

FIGS. 6 (a) and 6 (b) illustrate a holder for a doctor blade;

FIGS. 7 (a) and 7 (b) are schematic views illustrating a wiping member arranged in the case of using a back-and-forth rotating table according to a second embodiment of the present invention, and

FIG. 8 is an illustration of a printing process performed by an apparatus of the present invention.

Some embodiments of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings.

As shown generally in fig. 1 of the drawings, an inking unit of a known pad printing machine comprises an ink tank 1 in which a printing plate 2 is placed, a doctor blade 3 arranged to scrape off ink from the surface of the printing plate, and an ink return device 4 arranged to replenish ink onto the surface of the entire printing plate.

The inking member can be configured in one of two ways. One of the ink tanks is fixed and the doctor blade or the like is arranged to be horizontally movable. In another form the ink tank is arranged to move horizontally and the doctor blade or like member is fixed. In either case, the ink is scraped off as the doctor blade 3 moves to the right (as shown in fig. 1) relative to the gutter, and then the inking unit 4 returns or replenishes the surface of the plate as it moves to the left, which inking unit has the disadvantage, as mentioned above, that the ink thinners evaporate over time, thus necessitating the use of an automatic diluter addition unit. In addition to the above disadvantages, since two processes of ink scraping and ink returning are absolutely necessary, it is difficult to perform continuous printing at high speed.

Fig. 2 shows another known wiping device that prevents evaporation of the diluent. The ink of the device is contained in a completely sealed ink tank 5 which is placed on the printing plate 2. However, this device can only be used for printing plates with very flat surfaces and therefore can only be used for printing plates with very small plate sizes.

Referring now to fig. 3 (a) and 3 (b), there is schematically shown an apparatus of the present invention, suitably equipped with a chassis 10 on the body (not shown) of an ink pad printer. An ink tank cover 12 is provided with an ink supply port 6 and a doctor blade insertion port 12-1 and is fixed to the upper portion of the ink tank 13 by means of support arms 7, both of which are hinged to the respective brackets 9. Each support arm 7 is fixed to a predetermined position by a

screw

8, and 13 is arranged to be vertically and horizontally rotatable to facilitate the removal and attachment of the ink tank cover 12. The gutter is mounted on an indexing drive 11 and is arranged to be advanced in stepwise rotation. An annular low friction liner material 14 is disposed in the contact area between the gutter 133 and the gutter cover 12.

Referring to figure 4 (b) a printing plate 18 is held in place in the gutter 13 by screws 17. A doctor blade 16 made of a thin strip material is mounted on a doctor blade holder 20 and is configured to be brought into contact with the upper surface of the printing plate 18 through the doctor blade insertion opening 12-1. The blade 16 is a doctor blade holder bracket 19 secured to the ink tank cover 12.

An ink guide mechanism 15 in the form of a curved plate is attached to the lower surface of the gutter cover 12 and projects from the periphery of the printing plate 18 toward the middle thereof, so that ink discharged by the doctor blade is returned to the middle of the gutter. As shown in fig. 4 (a), it is preferable to install a similar ink guide member also in the middle of the cover to prevent ink from accumulating in the middle of the plate. A gap of about 0.5 to 1.0 mm is provided between the lower edge of the ink guide and the upper surface of the printing plate 18.

Fig. 5 (a) and (b) show a doctor blade holder 20 having a cylindrical shape, but the doctor blade holder 20 may of course be made to have a square shape or may be made to have a combination of a straight blade and a cylindrical blade as shown in fig. 5 (b) to prevent the thinner from being volatilized from the ink. In each case, the doctor blade holder has a central opening through which the ink pad moves up and down to draw ink up from the plate. A sealing plate 21 made of an elastic plastic is mounted on the cylindrical side of the doctor blade holder 20. The sealing plate 21 is thus arranged to prevent the diluent from volatilizing between the ink tank cover 12 and the doctor blade holder.

Referring to fig. 6 (a) and (b), the pins 22 at both ends of the doctor blade holder are attached to and connected to the doctor blade holder bracket 19. Preferably, a flower joint 23 or the like is used to mount the pin 22 for flexible movement of the doctor blade into contact with the upper surface of the plate.

The inking and wiping actions of the above-described device are as follows.

Referring to fig. 4 (a), the surface of the printing plate 18 is completely filled with ink except for a portion a surrounded by the doctor blade holder. Thus, in this case, portions of pattern B, C and D are in the same state, as they would have ink added to them by a re-inking process. When the indexing device moves past a stop, the portion of the design B is advanced to the printing position, whereupon the doctor blade is held in contact with the printing plate to scrape off excess ink from the portion of the design B, leaving ink only in the recessed portion thereof.

The apparatus of this embodiment is connected to a printer so that the printer pad begins to drop onto the portion of pattern B and then rises again. The other pattern portions C, D and a are now still filled with ink, after which the indexing device is moved past a stop to bring the pattern portion C into the printing position, while the ink pad has transferred ink to the print to be printed, and the pattern portion C of the printing plate follows. These processes are therefore repeated during the completion of a print job.

In this particular embodiment described above, the indexing transmission has four gears. However, the number of gears is not limited to four.

In another embodiment of the invention, a step-by-step rotary feed is coupled to the doctor blade, and a stationary printing plate is rotated to complete a single revolution by the rotary feed after ink on portion A of the pattern has been picked up by the pad and the doctor blade has returned. In this case, the print job can be completed in the same manner. The stepwise rotary feed means may be provided in two groups, one group being associated with the doctor blade and the other group being associated with the printing plate.

The indexing means 11 shown in figure 3 (b) may be replaced by a suitable back and forth rotating means, such as a pneumatic inversion table. At that time, the doctor blade member is modified as shown in fig. 7 (a) and (b). Referring to these figures, a cylindrical member 27 is either placed against the printing plate 18 by its own weight or is configured to be supported by the gutter cover 12, but a gap of about 0.5 mm is left between the printing plate and the cylindrical member 27. The cylindrical member 27 is thus configured to prevent the diluent of the ink from volatilizing. The position of the cylinder 27 is defined by the stop 26.

When the gutter is rotated clockwise, one doctor blade 24 drops to scrape ink, while the other doctor blade 25 remains clear of the plate in an idle state. In case the gutter is rotated in a counter-clockwise direction, the blade 25 falls and the blade 24 remains idle. Meanwhile, the ink guide mechanisms 15-1 and 15-2 are configured to be raised and lowered simultaneously with the

doctor blades

25 and 24, thereby allowing the ink to maintain a uniform thickness on the upper surface of the printing plate. The raising and lowering of the

doctor blades

24 and 25 and the ink guide mechanisms 15-1 and 15-2 may be accomplished by any suitable means, such as an air cylinder or the like.

According to the invention, the printing plate or doctor blade is configured to move either in a stepwise rotation or in a back-and-forth rotation. By means of this device, evaporation of the diluent is prevented, which allows high-speed printing on a wide plate surface without any special cylindrical doctor blade, which was not possible at that time in comparison with the prior art.

Although the printing method is explained with reference to fig. 4 (a), a printing job proposed according to the present invention can also be carried out in the following manner. Various patterns can be etched onto some of the pattern portions of the printing plate. A plurality of ink pads which can move vertically can be arranged on an indexing device which can rotate step by step. With this type of device, a plurality of different patterns corresponding to the number of gears can be printed one after the other. Furthermore, using a computer control, two indexing devices for the printing plate and pad can be used to select any desired pattern. Such a device is advantageous for a production line for printing different printed products, and allows printing to be done at any time, as well as for small batches of printed products, since no readjustment is necessary for each change of printed product.

Fig. 8 is a supplementary illustration of a printing method that can be carried out with the apparatus according to the invention, the three figures representing three steps in sequence from top to bottom: wiping, lowering and raising of the printing pad and ink recovery.

In the second process, the ink is retained in the recessed portion of the plate after the ink pad has been applied, the ink becomes somewhat hardened by the evaporation of the diluent, and the hardened ink cannot immediately return to its original soft state when new ink is applied thereto by wiping. In the third step, therefore, no relative movement is made between the printing plate and the doctor blade, but the diluent is let down through the freshly applied ink, so that the hardened ink has sufficient time to return to its original soft state (recovery).

Claims

1. A method of inking and doctoring a pad-printing press, by which ink is applied to a pattern provided on a printing plate, the printing plate is doctored, after which ink is sucked from recesses in the printing plate by means of a pad provided as a component of the press, characterized by the periodic operation of two steps, the first of which is the relative rotation of the printing plate (18) and the doctor blade (16) in a horizontal plane to effect the doctoring of the printing plate, and the second of which is the suction of ink from the printing plate (18) by the printing press pad, while the doctor blade (16) is in a stationary state.

2. Inking and doctoring method according to claim 1, characterized in that the relative rotation between the printing plate (18) and the doctor blade (16) is performed intermittently and always in the same direction, preferably with the doctor blade (16) held stationary and the printing plate (18) rotated relative to the doctor blade (16).

3. Inking and doctoring method according to claim 1, characterized in that the relative rotation between the printing plate (18) and the doctor blade (16) is performed in a back and forth manner, preferably with the printing plate (18) held stationary and the doctor blade (16) rotated relative to the printing plate (18).

4. A method of inking and doctoring according to any one of claims 1 to 3, wherein each cycle includes a third operation in which the plate (18) and the doctor blade (16) are not moved relative to each other, but the plate ink is returned.

5. A method of inking and doctoring according to any one of claims 1 to 3, wherein the ink covers the printing plate (18) in the gutter (13) except for the area over which the ink has been doctored.

6. A method of inking and doctoring according to claim 4, wherein the ink covers the plate (18) in the gutter (13) except where it has been doctored.

7. An inking and doctoring device for a pad printing machine, comprising a gutter (13) in which a printing plate (18) is accommodated and a doctor blade (16) is arranged to scrape off ink from the upper surface of the printing plate (18), and a transmission (11) adapted to produce a relative rotation between the printing plate (18) and the doctor blade (16) in a horizontal plane, characterized in that the printing plate (18) is of the plate type, the relative rotation between the printing plate and the doctor blade (16) being carried out in a horizontal plane, and in that the gutter (13) is provided with a gutter cover (12) which does not need to be opened when the pad is lowered, in order to minimize the evaporation of ink components.

8. Inking and doctoring device according to claim 7, characterized in that the doctor blade (16) is mounted on a stationary part and the drive is arranged to rotate the gutter (13) and the printing plate (18), preferably always in the same direction in an intermittent manner, for the doctoring of the printing plate (18).

9. Inking doctor apparatus according to claim 7 or 8, characterised in that the doctor blade (16) is configured to define a closed portion in which a design to be printed on the printing plate can be placed in response to relative rotation between the printing plate (18) and the doctor blade (16).

10. Inking and doctoring device according to claim 7, further characterized in that the gutter (13) and the printing plate (18) are mounted on a stationary member and the drive means (11) are adapted to allow the doctor blade (16) to move, preferably in a back and forth rotational manner, relative to the printing plate (18).

11. Inking and doctoring device according to claim 7, characterized in that two doctor blades (24, 25) are provided which are arranged to alternately contact the printing plate (18) depending on the direction of relative movement between the doctor blade (16) and the printing plate (18).

12. Inking and doctoring device according to claim 9, wherein two doctor blades (24, 25) are provided which are arranged to alternately contact the printing plate (18) depending on the direction of relative movement between the doctor blade (16) and the printing plate (18).