JPS5848456B2 - Stretching control device for web-type rotary printing presses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a roll-up method used for printing printed matter that requires not only high-precision color registration but also high-precision printing pattern pitch, such as continuous forms and packaging materials. The present invention relates to a stretching control device in a rotary printing press.

By the way, in a web-type rotary printing machine that performs printing while unwinding the printing material from a roll, it is essential to print with an appropriate amount of tension applied to the printing material in order to prevent the printing material from meandering or breaking. ing.

The appropriate tension is roughly determined by the material, dimensions, etc. of the printing material, and based on this, the tension control device in the printing machine is activated to maintain the tension of the printing material at the above value just before it reaches the printing section. Ru.

As a result, printed matter with good registration accuracy can be obtained after passing through the printing section of the printing machine.

However, for ordinary printed matter, the above constant tension control is sufficient as long as the color register matches, but it is still a problem for continuous slips and other printed designs that require pitch accuracy.

This is because the material, dimensions, etc. of the rolled body are not uniform over its entire length, and if the rolled body is made of paper, its properties may vary depending on the moisture content, history after papermaking, or changes in temperature and humidity in the atmosphere. As a result, the elongation characteristics change even during printing, and when the tension is removed after printing and the pattern returns to its original size, dimensional fluctuations occur between the patterns and the pitch changes.

For example, if the pitch changes, problems will occur in printed matter that requires a certain foot print, such as continuous forms, especially in the case of multi-part products that are made up of overlapping forms made of different materials, paper thicknesses, etc. The problem is that collation becomes impossible.

Additionally, packaging materials may have problems due to their relationship with processing machines such as cutting machines in the subsequent bag-making process.

The present invention has been made in view of the above points.

In other words, in the first machine, the printed matter is fed out from the body at a certain tension, and the printing material is fed out from the first and second parts with a fixed circumferential speed ratio.
Between the nip o-5, a constant tension of 1 is applied to create a tension of lr, and the above constant tension and the first,
The tensile rate between the first and second rollers that causes the above constant 0) elongation in the tension generated between the second rollers is the force [j (Toray's mark for the first 51
1 ↑ 1 71 J' Calculate the tensile rate of 1, and apply this tension to the 1st-2nd to 2nd [U-Ra circumference 5th gear] side] and mark Mt: 'J In order to create an equal pitch over the entire length of the object and send it to the mark IliiIJ section, I set 7. In this way, even after eliminating the stretch after printing, the pattern will have an equal pitch over the entire length of the object. ,,yo').

Hereinafter, we will explain the embodiments of the present invention based on the drawings. Explanation of the condition equipped in the material supply department 1゛ Prison C
In the figure, 10 is the roll Tfl body, 12 is the material to be printed that is fed out by the roll body, and 14 is the details. fft! 5
However, a predetermined El fi:j is a printing section (first unit i= )-U″j·-) with a cylinder tongue.

7. Then, the first and second printing parts are placed in the running path of the twin printed matter 12 between the roll body 10 and the printing unit 14.
0) One inch T7'['l.
}11. Between the first knob fJ=-ra 16 and the second-21 roller 18, tension (ii: j'7, i) and two devices 20.22 are provided, respectively.

In C KojJ2, - handling printed matter 12 is No. T = - Tsuburu rU
- Since the winding body 10 is unwound from the winding body 10 by the winding body 10 and the butot 1 is applied through the winding body 10 and the first and second winding body 10 (1) between the winding body 10 and the winding body 16 (1) and tension T.

Ga-j. rt1 can be obtained.

Next, a tension T1 is applied between the first and second nip rollers 1δ, 18, and the tension is +1. ,=>.

Nitsu-7゜Ii'l-ゞra 16 and 18 have a fixed circumferential speed ratio and r. ．． :t O, mark +jj, ljl part No. 1 drive lliI1124 gearbox, V9lJ :2
-c,i%l\...-1, the power is delivered via the continuously variable transmission 26, and the circumferential speed of the second nib LJ--ra 18 is set to be greater than the first one <{, , circumferential speed' [The two are rotated as one unit.

In Sub-5), the elongation caused by ♀r↑ in Ku2-2 is constant, and the tension difference 'i', -'ro is proportional to the elastic modulus of the printing substrate.

The printing unit 14 is rotating at a high speed with a constant circle speed, and between this and the second Nitzf theory -ra 18, the object is subjected to tension T2.

1: τI tension ([1l] The constant device 20, 22 includes, for example, rollers 28, 30, a load cell 36, 38 supporting the D-ra, etc., and the tension T.

, T1 are measured respectively.

According to the present invention, the measurement signal from this device is sent to the arithmetic unit 40, processed, and used to control the transmission.

Next, to explain in detail the control in -L, first,
In this light ζ, as shown in FIG. 2, each arbitrary part of the flow force direction of the marked &l1 object 12 AL4 + 2 + 3! :
Mainly, the elongation characteristics {4: are different from each other and 1. ．． / , constant tension T.

(See FIG. 3A) Below, it is assumed that elongation/\eo changes as shown by the solid line and chain line in FIG. 3B.

However, since the printing material then enters between the first and second nip rollers 16 and 18 and is stretched at a constant tension α1, the above ``-1,273'' is -・a constant length, ・e ′ is further extended.

Here, the tensile rate α1 is the circumferential speed 1 of the first nip roller.
It refers to the rate of increase in the peripheral speed of the second Nitsuburo to be sealed.

Therefore, if the Young's bundle E1 thickness h1 width W of each portion At t7 ys of the printing material is set, then the following equation is established from Hooke's law [11].

T,=To+E-b・W・α1・・・・・・・・・・・・
(1) Furthermore, if the ratio of increase/decrease in the fixed speed of the printing section to the circumferential speed of the first nib roller is taken as the tensile rate α2, then the following equation holds true.

T2=To-1-E-b-W・α2・・・・・・・
・・・・・・・・・・・・・・・(2) Here, if we change α2 so that -Example becomes T2-T1-To, (1) From the formula, the stretching ratio of the printing material under the tension '■'2 becomes T2E-b-W', which is a constant value, and as shown in Fig. 3, the stretching ratio of the printing material (
Each part of the snout, A, , A2, and A3, is elongated and has the same length.

As a result, the printing substrate 12 has a certain elongation in each part.
I is led to the printing section 14 as it is, and after being printed in one color or multiple colors in the printing section 14, it is discharged outside the machine and the tension is removed, and as shown in Fig. 2, it is elastically Hill” △l
〃 disappears, and the pattern pitch returns to its original size.

(5) aside, To and T1 are each tension measuring device 20,
22, and since α1 is set in advance, α2 is measured by the arithmetic unit 4 consisting of a known circuit.
0 is easily determined and output as a signal.

This signal is sent to the transmission 26 and is used to change the speed of the first nip roller.

In addition, the formula (5) has a constant determined experimentally and empirically.Although the formula (5) is a formula when α1 is given as the stretching ratio of the printing substrate under T2, it is also possible to obtain an arbitrary stretching ratio C. You can also do that if you want.

By the way, in order to obtain constant stretching under tension T2 as described above, the condition T2-T1-To should be satisfied.

To achieve this, it is possible to directly control T2 so as to satisfy this condition, but in actual printing presses, it is unavoidable that slippage occurs between the printing cylinder and the printing material in the printing section. Moreover, this slip rate changes depending on conditions such as printing pressure.

Therefore, the value of the tension T2 that provides constant stretching varies considerably depending on the slip ratio.

For example, if slip occurs in the printing section and the amount of material to be printed from the printing section decreases, the tension T2 tends to be smaller than when there is no slip;
According to the method of controlling T2, since an attempt is made to maintain T2 at the same value as in the case without slip by changing α2, the stretching ratio becomes large.

On the other hand, the method of the present invention has the advantage that the tension ratio α2 is constant regardless of the presence or absence of slip, and when slip occurs, the tension T2 becomes smaller by itself, so that the stretching ratio does not change.

As described above, the present invention provides first and second nip rollers and a tension measuring device with fixed circumferential speed ratios between the winding body and the printing section in a winding type rotary printing press, Based on the constant tensile rate given between the nip rollers and the measured value of the tension measuring device, the arithmetic unit calculates the tensile rate of the printing section with respect to the first nip roller, and based on this, the transmission is controlled so that the elongation of the printing material is equalized over the entire length. After that, it is sent to the printing department.

Therefore, according to the present invention, even if the elongation characteristics of the printing material partially change, uniform elongation is caused over the entire length of the printing material when it is introduced into the printing section, and after printing a pattern with a constant pitch in the printing section, By releasing the tension, each part of the printing medium can be returned to its original size and the pattern pitch can be made the same.

This means that it is possible to optimize the printing of continuous forms, packaging materials, etc., which require precision in the pattern pitch after printing.

Of course, the present invention may also be applied to ordinary printed matter to improve the accuracy of these pattern pitches.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a printing material supply section of a winding type rotary printing press to which a stretching control device according to the present invention is applied. FIG. 2 is a diagram showing the relationship between tension and elongation in each portion AI, A2, and A3 of the printing material. 3A and 3B are explanatory diagrams showing the relationship between each position in FIG. 1, the tension applied to the printing material, and the elongation occurring in the printing material. 10... Rolling body, 12... Printing material,
14...Printing section, 16...First nip roller, 18...Second nip roller, 20,2
2... Tension measuring device, 26... Transmission, 40... Arithmetic device.

Claims (1)

[Scope of Claims] 1. A stretching control device for a web-type rotary printing press comprising the following items. a. First and second nip rollers with fixed circumferential speed ratios, which are provided in the running path of the printing material from the roll of the printing material to the printing section. b. A tension measuring device provided between the wound body and the first nip roller, and between the first nip roller and the second nip roller. C. A constant tensile rate α between the first and second nip rollers
1 and the two tensions T obtained from the above two tension measuring devices one by one as the printing medium travels. , T1, the tensile rate α2 of the printing cylinder in the printing section with respect to the first nip roller causes a constant elongation of the printing material between the first nip roller and the printing section.
A computing device that computes. d. A transmission for the first nip roller that is controlled based on the tensile rate α2 obtained by the arithmetic device.