JP2005131900A - Ink supply arrangement of letterpress machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink supply arrangement which cancels the hysteresis of an ink film thickness on the roller hysteresis side by means of a mechanism using no anilox roller, but having a form roller of an elastic body, in regard to the ink supply arrangement for letterpress printing. <P>SOLUTION: The diameter of a plate cylinder is made equal to that of the form roller. Thereby the transfer of ink between the plate cylinder and the form roller is so made that the ink joins and separates at the same respective regions thereof. Consequently a prescribed film thickness is always maintained and the effect of the hysteresis thereof can be canceled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink supply device for a relief printing press including flexographic printing.

  In order to form a uniform ink film thickness on the plate surface, in flexographic printing, an anilox roller has been conventionally used as a member for supplying a fixed amount of ink to the plate surface. Since the anilox roller having a hard surface is in contact with the plate surface, the plate surface needs to have elasticity. Further, since the cell capacity of the anilox roller is constant, the amount of ink could not be adjusted.

Another conventional technology for letterpress printing is to reduce the ink history that occurs in the image area and non-image area of the plate by arranging multiple ink forming rollers and a large number of rollers between the ink forming roller and the ink source roller. Ink supply device.

The problem to be solved is to supply a uniform ink without an anilox roller, to be able to adjust the ink supply amount, and to make the ink form roller in contact with the plate an elastic roller. Since the anilox roller in contact with the printing plate has a rigid surface, it has an elastic structure on the printing plate side to improve ink delivery. For this reason, the relief height is increased and the cushion is laid under the plate, making it difficult to support high-definition printing. Further, the ink history reduction method using a large number of roller groups is to use an ink supply device using a small number of rollers because the apparatus is large and requires maintenance.

In order to solve the above problems, according to the present invention, the plate cylinder diameter and the ink form roller diameter are made equal. The ink transfer between the plate cylinder and the ink form roller is merged and separated at the same site, so that the printing surface can always be printed with a constant film thickness without being influenced by the ink history.

An ink supply device for each color is provided by a mechanism that has a total of three cylinders, one ink base roller on the surface of smooth and high hardness, one cylinder on the elastic surface, and one plate cylinder. The

Since the ink supply amount can be controlled by the speed difference between the ink base roller and the ink form roller, an ink supply device that can control the ink amount to the substrate, that is, the ink film thickness is provided.

Without using an anilox roller, it was possible to supply ink from an ink source roller with a smooth surface using a conventional ink doctor, so the air supply caused by an anilox roller, the decrease in the amount of ink supplied due to wear, depending on the printed matter The problem of changing the anilox roller due to the change in the number of wires was solved.

Because the ink form roller is made of an elastic material, it is gentle to the plate surface. The plate can harden the relief, increase the durability of the plate, reduce the relief height, and support high-definition printing. The cushion is no longer needed.

By changing the peripheral speed of the ink base roller, the ink film thickness on the substrate can be controlled and the printing density can be varied.

In conventional letterpress printing with high plate hardness, the ink history was reduced by using multiple ink form rollers. However, the plate cylinder, ink form roller, and ink source roller make up an ink supply device with one cylinder each. And miniaturized.

The best mode for carrying out the invention will be described with reference to the drawings based on the embodiments.

FIG. 1 shows an example of roller arrangement of the ink supply apparatus of the present invention. The ink form roller 12 is in pressure contact with the plate cylinder 11 and the ink base roller 13. The large diameter portion of the ink base roller 13 is dipped in the ink 16 in the ink pan 17 and scraped off by the ink doctor 15, and the ink with a uniform film thickness is supplied to the ink form roller 12. The ink form roller 12 and the plate cylinder 11 have the same diameter and are rotationally driven at the same surface speed by a driving device not shown in the drawing. The ink supplied to the ink form roller 12 is supplied to the image line portion at the top of the plate relief of the plate cylinder 11, and the ink is transferred from the top of the plate relief of the plate cylinder 11 to the substrate 10 by a conventional printing technique and printed. The Since the ink form roller 12 and the plate cylinder 11 are press-contacted and have the same diameter, the positional relationship in the circumferential direction between the ink form roller 12 and the plate cylinder 11 is always constant, and the nip position relationship is not changed and the ink film is always constant. Thickness is provided, and good printing can be performed without leaving an ink history.

FIG. 2 schematically shows the ink film thickness in the image area of each cylinder. When the ink film thickness is obtained with an ink transfer rate of 50%, it is as follows. The supply side film thickness Tpa ink of the plate cylinder 11 is separated and transferred to the ink film thickness Tt and the history side film thickness Tpb of the plate cylinder 11 on the base material 10, so that Tpa = Tt + Tpb (1). Since the ink transfer rate is 50%, Tpb = Tt (Equation 2). From Equation (1) and Equation (2), Tpa = 2Tt... Equation (3). Similarly, at the nip portion between the plate cylinder 11 and the ink form roller 12, the hysteresis side film thickness Tpb of the plate cylinder 11 and the supply side film thickness Tfa of the ink form roller 12 merge to obtain the supply side film thickness Tpa of the plate cylinder 11. Since it is separated into the history side film thickness Tfb of the ink form roller 12, Tpa = Tfb = 2Tt (5) and Tfa = 3Tt (6). Further, when the transition between the ink base roller 13 and the ink form roller 12 is the peripheral speed Vd of the ink base roller 13 and the peripheral speed Vf of the ink form roller 12, the film after separation of the ink base roller 13 and the ink form roller 12 is obtained. the thickness td, tf are known relationship (td / tf) = (Vd / Vf) 1/2 ···· formula (7). Here, considering the apparent equivalent thicknesses Tdb and Tfa when the peripheral speeds are the same, similarly, Tfb + Tda = Tfa + Tdb (8) and Tfa = Tdb, so Tda = 4Tt. (9) Tdb is immersed in the ink 16 in the ink pan 17 and has no history. Therefore, it is understood that when the equivalent film thickness on the supply side of the ink base roller 13 is Tda = 4 Tt by the ink doctor 15, the film thicknesses on the ink supply roller supply side and the plate supply side are always constant at 3 Tt and 2 Tt, respectively. It was. In each roller, the difference in film thickness between the supply side and the history side is a constant Tt. Therefore, by making the plate cylinder diameter and the ink form roller diameter the same diameter, the nip between the plate cylinder and the ink form roller merges and separates in the same positional relationship, so the image area is always the same area as the image area. The ink film thickness is always kept constant, and the influence of this history can be eliminated.

Next, the non-image portion will be described with reference to FIG. Since there is no consumption of ink in the non-image area, if the peripheral speed of each roller is the same, the film thickness is the same from Equation (7). That is, if the apparent equivalent thickness Tda of the ink base roller 13 is 4 Tt, which is the same as that of the image line portion, Tfa, Tfb, Tdb are also 4 Tt and are always constant. In letterpress printing, the ink film thickness Tt of the substrate is usually about 1 to 3 micrometers, and the equivalent film thickness Tda of the ink base roller is about 4 to 12 micrometers. If the relief height of the plate is 4 to 12 micrometers or more based on the relief distortion caused by the nip between the plate cylinder and the ink form roller, the ink will not transfer to the non-image area of the plate.

As the body diameter of the elastic body, the diameter of the true rolling may be adopted in the pressure contact state.

As an ink supply device, it is constituted by three cylinders of an ink original roller 13, an ink form roller 12 and a plate cylinder 11 for each color. The surface of the ink base roller 13 is smooth and hard finished by chrome plating or the like so as to withstand the scraping doctor, but an anilox roller is not necessary. The surface of the plate cylinder 11 and the surface of the inking roller 12 having the same diameter are made of an elastic body such as dust, and can be in soft contact with the relief on the plate surface. The plate cylinder and the ink form roller are preferably reduced in weight, such as a hollow or a shaft exchange type, by an existing technique in order to facilitate the exchange work.

According to another preferred embodiment of the present invention, it is useful when the plate cylinder diameter is small, with a mechanism in which the ink form roller has a double diameter of the plate cylinder.

  It can be used in an ink supply apparatus for letterpress printing machines including flexographic printing.

1 is a diagram illustrating an ink supply device according to Embodiment 1 of the present invention. FIG. Explanatory drawing which shows the ink film thickness of the image part of the ink supply apparatus by this invention. Explanatory drawing which shows the ink film thickness of the non-image part of the ink supply apparatus by this invention. It is a figure which shows the conventional ink supply apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base material 11 Plate cylinder 12 Inking roller 13 Ink former roller 14 Impression roller 15 Ink doctor 16 Ink 17 Ink pan 21 Anilox roller
T t Ink film thickness on substrate
T pa Ink film thickness on the ink supply side of the plate cylinder
T pb Ink film thickness on the history side of the plate cylinder
T fa Ink film thickness on the ink supply side of the ink form roller
T fb Ink film thickness on the history side of the ink form roller
T da Ink thickness on the ink supply side of the ink source roller
T db Ink film thickness on the history side of the ink source roller

Claims (3)

An ink supply unit for letterpress printing in which the diameter of the plate cylinder 11 and the diameter of the ink form roller 12 are equal. In one-color printing, in an ink supply apparatus constituted by a total of three cylinders of a plate cylinder 11, an ink form roller 12, and an ink origin roller 13, the ink origin roller 13 does not use an anilox roller and has a smooth surface. 2. The ink supply unit according to claim 1, wherein the ink supply roller is formed of a member, and the ink form roller is formed of a surface of an elastic material. The ink supply unit according to claim 2, wherein the ink film thickness on the substrate 10 can be controlled by changing the peripheral speed of the ink base roller 13.

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