JPS6395945A - Printing device - Google Patents

Abstract

PURPOSE:To print over an arbitrary length without replacing a form cylinder, by providing a velocity controlling means for varying the feeding velocity of a web and the circumferential velocity of a printing means at predetermined change rates and a contact means having an appropriate radius of curvature and bringing the web into contact with the printing means. CONSTITUTION:A printing plate is fitted over substantially the entire circumference of a form cylinder 50, and an appropriate quantity of an ink is supplied thereto by an inking device 60. The form cylinder 50 is driven by a motor 54 through a gear 52. The rotation of the gear 52 is transmitted also to a speed change gear 70, the output of which is transmitted to a web-driving roll 74 through a gear 72. Therefore, the feeding velocity of a web 20 paid out from an unwinder 22 is controlled to a predetermined ratio to the circumferential velocity of the form cylinder 50. The web 20 is fed past a guide roll 78 while being pulled by a rewinder 24, and is brought into contact with the form cylinder 50 through a contact means 30. When a contact part of the means 30 has an appropriate radius of curvature, it is possible to obtain an enlarging factor 1.13 and a reducing factor 0.89 thereby covering all repeat lengths by 2-5 kinds of form cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for printing on a running web, and more particularly to a so-called all-size rotary printing apparatus.

(Prior Art) In a web rotary printing press, attempts have been made to print in all dimensions (i.e., repeat length) without replacing the plate cylinder, which is one of the printing means (for example,
Publication No. 7159).

However, in the conventional apparatus, the repeat length is changed by rapidly changing the speed of the web or the plate cylinder, and there are still problems to be solved. Typical examples are listed below.

■ Rapid acceleration and deceleration of the web easily causes the web to break, making registration difficult.

If the O-plate cylinder is rapidly accelerated or decelerated, a horse-horsepower electric motor is required and registration becomes difficult.

As a result of intensive research to solve these problems, the inventor of the present invention came to the conclusion that by varying the running speed of the web and the circumferential speed of the printing cylinder (an example of printing means), it is possible to print with any repeat length. and have already filed several patent applications for inventions related to this (for example, Japanese Patent Application No. 61-25367, Japanese Patent Application 'W'
61-71966, etc.).

After further research, the inventor found that although the printing cylinder and the web are in line contact, they have a certain width, and the size of this width affects the printing finish.
It has been found that printing quality can be improved by making this line width as narrow as possible.

(Problems to be Solved by the Invention) The present invention is based on the above knowledge, and the objects of the present invention are as follows.

■Due to the difference between the running speed of the web and the peripheral speed of the printing means,
To reduce blur in printing as much as possible.

■ Minimize the negative impact on the web caused by the contact means (equivalent to a conventional impression cylinder) as much as possible.

○ The contact means should be able to uniformly bring the web into contact with the printing means.

Other objects to be achieved by the invention will become clear from the description and drawings that follow.

(Summary of the Invention) Therefore, the gist of the present invention is that, in a device that prints on a running web, a speed regulating means for making the running speed of the web and the circumferential speed of the printing means different at a predetermined rate of change. and abutting means that contacts the entire web printing means and has a radius of curvature of 2 mm to 70 mm.

(Structure and operation of the invention) Details of the present invention will be described below with reference to embodiments illustrated in the drawings, but it goes without saying that the present invention is not limited to these embodiments.

FIG. 1 is a developed view of a printing plate 10 used in the apparatus of the present invention. This printing plate 1O is one of the printing means, and in the case of letterpress, it is a flexographic printing plate, in the case of photosensitive resin printing plate, and in the case of planographic printing, it is PS.
In the case of plates and intaglios, it is a photosensitive sheet that can be wrapped around the printing cylinder. In addition, if a printing plate is not attached to the printing cylinder, for example, if an engraving roll is used as the printing cylinder, this printing cylinder itself becomes the printing means,
In the case of offset printing, a printing cylinder, usually called a blanket cylinder, corresponds to the printing means. In this specification, the printing plate 10 will be mainly explained as a representative printing means, but it goes without saying that the printing means is not limited to printing plates.

The printing plate 10 described above is one in which the actual repeat length R is larger than the printing direction length RP of the printing plate, that is, one on which enlarged printing is performed. Approximately 50% using this printing plate 10
% enlargement printing, a printing pattern as shown in FIG. 2 is obtained. Therefore, the pattern on the printing plate 10 is reduced in size in the rotational direction from the actual printing pattern during plate making.

It goes without saying that the printed portion does not need to cover the entire repeat length R, and can be arbitrarily selected within that range. Note that registration can be performed by printing all 12 register marks in the same way as in normal printing.

On the other hand, if you want to make the repeat length R shorter than the length of the printing plate RP, make the plate at different wavelengths in the direction of rotation of the printing plate 10, and set the running speed of the web relative to the circumferential speed of the printing cylinder during printing. By making the pattern smaller, a reduced pattern is printed.

FIG. 3 shows a typical embodiment of the apparatus of the present invention, which performs printing by expanding and contracting the pattern of the printing means in the rotational direction of the printing cylinder, that is, in the running direction of the web.

In order to print by enlarging or reducing, the circumferential speed of the printing cylinder 50 is uniformly changed at a predetermined ratio based on the running speed of the web, and the length of the printed pattern is similarly measured. There are methods such as adjusting the running speed of the web 100 or the circumferential speed of the printing cylinder 50, and controlling the running speed of the web 10 at a predetermined ratio based on the circumferential speed of the printing cylinder 50.
In short, it is sufficient as long as the running speed of the web 10 and the circumferential speed of the printing cylinder 50 are always kept at a constant ratio. Which of the above methods to adopt depends on conditions such as whether to use an in-line type or an offline type, but in Fig. 3, the printing cylinder 50
An example is shown in which the running speed of the web 20 is controlled based on the circumferential speed of the web 20.

A printing plate 10 as shown in FIG. 1 is attached to the printing cylinder 50 over almost its entire circumference, and an appropriate amount of ink is supplied to the printing plate 10 from an inking device 60. When enlarging printing with the printing plate 10 as a reference, an amount of ink is applied that is approximately proportional to the enlargement ratio, and when performing reduction printing, an amount of ink that is approximately proportional to the reduction ratio is applied.

The amount of ink can be adjusted, for example, by adjusting the clearance between the pumping roll 62 and the transfer roll 64 in the roll coater type inking device 60 shown in FIG. 3, or by changing the rotation ratio of these rolls 62 and 64. It can be done by

The printing cylinder 50 is driven by a motor 54 via a first gear 52 . The power of the first gear 52 is separately supplied to the second gear 52.
A transmission 70, which is one of the speed regulating means, is connected via a gear 56.
transmitted to. This transmission 70 is provided with a gear ratio setting tool and a scale so that the gear can be shifted at a predetermined ratio, but these are not shown because they are conventional.

In addition, in FIG. 3, a mechanical transmission device 70 is used as a speed regulating means.
However, it is needless to say that it is not limited to a mechanical type and may be an electrical or electronic type.

The output from the transmission 70 is transmitted via a third gear 72 to a web drive roll 74, with a nip roll 76 in contact with the drive roll 74 via the web 10.

Therefore, the running speed of the web 10 fed out from the unwinder 22 is controlled to a predetermined ratio to the circumferential speed of the printing cylinder 50.

The web 10 whose running is controlled to a predetermined ratio is a rewinder 2.
4, it contacts the printing cylinder 50 via the guide roll 78. In ordinary printing apparatuses, an impression cylinder is used to abut the web, but the apparatus of the present invention differs from these in that it uses abutting means 30 that is not limited to a cylinder.

When the contact means 30 is a rotating roll, the diameter of the roll is preferably 10 mm to 140 mm, more preferably 20 mm to 100 mm. The most preferred range is 20 mm to 50 mm.

For more details, please refer to the description of the embodiments below.

Although these values are expressed in terms of diameters for simplicity, it is obvious that if these values are expressed in terms of radius of curvature, the value will be exactly half that value.

If the diameter of the roll is less than 10 mm, it becomes difficult to manufacture the roll itself, and it becomes extremely difficult to support the roll in a rotatable manner, which is not practical.

From the point of view of eliminating deflection of the roll, the larger the diameter of the roll, the better.

On the other hand, if the diameter of the roll is increased to about 200 mm, the print finish will deteriorate significantly. The limit is a roll diameter of about 140 mm.

The rate of change between the web 10 and the printing cylinder 50 is 1.13 or 0.8
9, a marginal zone equivalent to that of normal printing can be obtained when the roll diameter is approximately 50 mm, and a finish that is almost the same as constant speed printing is obtained when the roll diameter is approximately 30 mm. .

The above-mentioned change rates of 1.13 and 0.89 indicate that when three types of printing drums 50, large, medium and small, are prepared, all dimensions (however,
The maximum dimension is limited to 1.13 times the circumference of the large printing drum)
These are the typical maximum and minimum values of the rate of change to cover. In other words, if the speed of each printing cylinder or web can be varied at a ratio of 0.89 to 1.13 times that of constant speed printing, all dimensions within the above-mentioned maximum dimension can be covered.

When using two types of printing drums 50, large and small, use 084 to 1.1.
9 times, 0.91 to 1.09 times for 4 types, 5
In the case of different types, all dimensions can be covered within a variable range of 0.93 to 1.07 times. There are 6 types of printing drums 50
There is no big difference in printing accuracy even if you use more than one.

In the case of flexible printing, it is sufficient to have two to five types of printing cylinders, and especially when high-definition printing such as process color printing is not performed, two or three types of printing cylinders are sufficient.

If only one type of printing cylinder is used, the variable range becomes large, making it difficult to perform high-precision printing. As a result of the experiment, the marginal zone when printing with a change rate of 142 times using an impression cylinder with a diameter of 100 mm was comparable to that of sheet printing on corrugated board using a flexographic method. As can be seen from the examples, when the rate of change is reduced, the marginal zone is also reduced, so if one type of printing cylinder is used, sufficiently beautiful printing can be obtained within a limited variable range.

FIG. 4 is a side view showing details of the web abutting means 30;
The contact portion 32 is made of a rotatable roll.

Since this roll 32 has a relatively small diameter (a radius of curvature of 10 to 25 mm is required), it is susceptible to deflection. Therefore, when the printing width becomes 1 to 2 meters, it becomes impossible to obtain an appropriate pressing force, so a knock-up means 34 is provided locally so that a uniform suppressing effect can be obtained over the entire area. The backup means 34 is composed of, for example, a roller or a ball bearing. Although the arrangement interval depends on the diameter of the roll 32, it is preferable to arrange the arrangement at a pitch of about 20 to 30 centimeters. If the roll 32 is facing downward, the roll 32 will bend downward, so it is best to pull it upward with the magnet 36. Of course, the magnet 36 may be a permanent magnet,
An electromagnet may also be used.

If the mechanical precision of the contact portion 32 is to be increased, the frame 38
The mechanical strength of the dog should be the same as that of the dog.

Unlike the above-mentioned roll, when the abutting part does not rotate as shown in FIG. 5, the abutting means 40 itself can be thickened, so the curvature of the abutting part 42 should be made extremely small. Can be done. However, this abutting portion 42 is formed at an angle to the web 10 so that the printing cylinder 50
If the curvature is too small, the web 10 may be broken or warped.
This will cause wrinkles and cracks. For example, if the web 10 is a corrugated cardboard liner (2209/m"), it is almost impossible to reduce the radius of curvature to less than 5 mm. If the web 10 is a thin flammable plastic film, the radius of curvature can be reduced to less than 5 mm. It is possible to reduce the thickness to about 2 mm.

The web 10, which has been printed through the abutting means within the range described above, is wound up by the rewinder 24 in a conventional manner to complete the printing.

In FIG. 3, a monochrome printing apparatus is illustrated, but the invention is not limited to this, and it goes without saying that a multicolor printing apparatus can be used.

(Example) Using the apparatus shown in FIG. 3, a printing test was conducted using the radius of curvature as a parameter. The main test conditions are as follows.

Printing speed: 100 meters/min Diameter of stamp cylinder: 260 mm Plate: Photosensitive resin plate for flexographic printing. 7mm thick. (Manufactured by Asahi Kasei Corporation. Product name: APR). Note that the dimensions of the printing plate are expanded or contracted according to the rate of change.

Planned printing width of test print line = 04 mm Orientation of test print line: Parallel to the axis of printing cylinder Web used: Corrugated board liner (K liner, basis weight 220 g/m2) Ink used:
Water-based flexographic ink for corrugated board liner Change rate: 1.13 times when enlarged, 0.89 times when reduced The width of the thin printed area was measured using a loupe with a scale.

Incidentally, the thinly printed portion appears at the center of the drawing line when printing at the same size, at the rear in the running direction of the web when printing is enlarged, and at the front when printing is reduced. The results are shown in the table.

*I A is the width of the thin part (unit: millimeters) *2
As for B, it can be seen from the results that the width of the entire print line (unit: millimeter) or more is that, in principle, the smaller the radius of curvature, the better the print finish. However, when the web is a corrugated liner, the liner is thick, so it is not preferable to make the radius of curvature smaller than 10 mm because bending the liner will cause warping and internal stress.

On the other hand, the print finish is almost the same as full-size printing when the radius of curvature is approximately 15 mm, and when the radius of curvature is approximately 10 mm.
Even if the size is reduced to millimeters, the print quality will not be any better. This is considered to be due to the characteristics of the flexo printing method itself.

The enlargement and reduction ratios shown in the table represent the range that can cover all repeat lengths if there are three types of printing cylinders: large, medium, and small. In addition, when using three types of printing cylinders (dog, medium, and small), use a turret type, and when one of them is printing, the printing plate can be attached to and removed from the other two, reducing the loss when changing plates. It can save time.

(Effects of the Invention) As described above, the apparatus of the present invention has a speed change means that makes the running speed of the web different from the circumferential speed of the printing cylinder, and a contact means with a small radius of curvature, so there is no need to replace the printing cylinder. It has the advantage of being able to perform printing of arbitrary length.

Even if high-precision printing is desired, it is sufficient to have two to five types of printing cylinders, which not only reduces printing costs but also greatly simplifies inventory management of printing cylinders. In particular, when using two or three types of printing cylinders, a turret type can be used, so a storage space for the printing cylinders is not required.

Since there is no sudden acceleration or deceleration of the web or plate cylinder, there is an advantage that registration of each color is easy, there is no possibility of web breakage, and the electric motor does not require a horse-powered motor.

[Brief explanation of the drawing]

FIG. 1 is a developed view of a printing plate used in the device of the present invention, FIG. 2 is a plan view of a sheet printed by the device of the present invention, FIG. 3 is a configuration diagram showing one embodiment of the present invention, and FIG. 4 5 is a side sectional view of the abutting means used in the apparatus of the present invention, and FIG. 5 is a side view showing another example of the abutting means. 20... Web, 30... Contact means, 50... Print cylinder, 60... Inking device, 70... Transmission device.

Claims (6)

[Claims] (1) In a device that prints on a running web, (a) speed regulating means for making the running speed of the web and the circumferential speed of the printing means different by a predetermined rate of change; (b) printing the web; A printing device comprising: abutting means that is brought into contact with the means and has a radius of curvature of 2 mm to 70 mm. (2) The radius of curvature of the abutment means is 2 mm to 2 mm.
A printing device according to claim 1, characterized in that the diameter is 5 mm. (3) The printing apparatus according to claim 1, wherein the contact means is a roll. (4) The printing apparatus according to claim 3, wherein the roll is supported by backup means. (5) The printing apparatus according to claim 4, wherein the backup means is a magnet. (6) The radius of curvature of the roll is 5 mm to 25 mm.
The printing device according to any one of claims 3 to 5, characterized in that the size is millimeters.