SU1735055A1 - Method to control tension of band material in printing machine - Google Patents

Abstract

SUMMARY OF THE INVENTION: A method for controlling the tension of a tape material in a printing machine consists in transporting the belt between pulling rollers at a speed of 0.06-0.1% more than between the cylinders of the printing pair. 3 il.

Description

The invention relates to intaglio printing processes on polymeric tape materials, preferably polyvinyl chloride heat shrinkable tubular film.

There is a method for adjusting the tension of a material in a printing machine using a winding mechanism.

The disadvantage of this method is that it does not provide an exact control of the material tension, since the pulling force varies with the radius of the winding of the material roll in the winding mechanism.

The closest technical solution is a method of controlling the tension of the material in a printing machine, in which the belt is transported by pulling rollers at a speed exceeding the speed of belt transport in the cylinders of the printing pair using a stepless adjustable drive.

The disadvantage of this method is that in the practice of operating printing machines for intaglio printing on ribbon polymeric materials, for example, polyvinyl chloride heat-shrinking flat-rolled tubular films, the adjustment of the edge of the material in the printing section and printing products go into rejects through the printing machine. This is due to the fact that these printed materials have a saber shape and the length of the material passing through the printing pair per unit of time is unequal. This causes the material to warp and go away with respect to the printing elements of the plate cylinder. In practice, when posting such materials, the tension of the material is increased. But this can lead to damage, since the heat-shrinking films are very sensitive to the action of tensile stress.

The purpose of the invention is to improve the quality of printing on polyvinyl chloride heat shrinkable tubular film by optimally extending it, in addition, it is possible to reduce the technological downtime of printing equipment and

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to expand the technological capabilities of the printing machine.

This goal is achieved by the fact that in the method of controlling the tension of the tape material in a printing machine, which consists in transporting the tape between pulling rollers at a higher speed than between the cylinders of the printing pair, the ribbon is transported between pulling rollers at a speed of 0.06 -0.1% exceeding the transportation of the tape between the cylinders of the printing pair.

It was established experimentally that transporting the ribbon between the pulleys with a speed of 0.06-0.1% greater than the transport of the ribbon between the cylinders of the printing pair, improves the quality of the printed material, mainly polyvinylchloride heat shrinkable tubular film, by elongating the printed film material since it is known that

Al li-l VBt-Vnt (VB-Vn) t, where I is the initial length of the sealing material in the working area (between axes of rollers and axes of cylinders of the printing pair), mm;

t is the time during which the material to be printed passes through the working area, s;

And - the length of the printed material passing through the working area under the action of pulling force during the time t, m;

And I - absolute elongation of the material, m;

VB - the linear speed of the conveyed belt between the tons of rollers, equal to 1,0006-1,001 m / s;

Vn is the linear speed of the conveyed belt between the printing cylinders of the printing pair, equal to 1 m / s.

r Al li-l VBt-Vnt

Ј IIVn t

 t (VB-Vn), Qi06 ОЛ) o / o i V n t

where Ј is the relative elongation or deformation of the stretch of the material being printed,%.

Transporting the tape between pulling rollers at a speed that is 0.06-0.1% higher than the transportation of the tape between the cylinders of the printing pair provides an increase in the quality of the printed material by optimal elongation, which allows to correct saber visibility and eliminate the possibility of creeping of the printed material

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form cylinder. The correction of the saber material is ensured by the fact that when the material is stretched, its shorter longitudinal layers stretch by a larger amount than the others. Analysis of the saber-like material showed that the maximum difference in the lengths of the edges (longitudinal layers) of the material does not exceed 0.06%. Therefore, accordingly, when the linear transport speed difference between the pulleys and the linear transport speed of the ribbon between the printing cylinders of the printing pair is less than 0.06%, the quality of the printed material decreases, as saber remains, the material slides over the printing cylinder and is observed lateral displacement of the printed material. When the difference between the linear speed of transporting the ribbon between the pulleys and the linear speed of transporting the ribbon between the printing cylinders of the printing pair is greater than 0.1%, the quality of the printed material itself decreases, as material deterioration is observed as a result of the heat shrinkable polyvinyl lorid film is a glassy polymer characterized by the following features. To obtain elastic, reversible tensile deformations of a glassy polymer, it is necessary to load it very slowly. With an increase in the loading rate, the behavior of the vitrified polymer is increasingly approaching the behavior of a fragile body, i.e. the polymer begins to break when a very small amount of deformation occurs. At a very low loading rate (stretching rate), the macromolecule sections have time to orient themselves in the force field and the chemical bonds do not break in the macromolecules, which prevents the polymer from deterioration. When posting material through the press, the maximum amount of tensile strain is determined as follows.

Since Ј max I, where L I max - the maximum absolute elongation, m;

 max A I max Ј max I.

then v n,

where VHMaKC is the maximum loading rate, m / s;

t is the time during which the material to be printed passes through the working area, p.

i Therefore, if t

w m V p

Max

where Upmax is the maximum linear speed of the conveyed belt between the printing cylinders of the printing pair, m / s, w max.

TO VH - Ј max Vn.

From this formula, it can be seen that the maximum amount of tensile strain limits the maximum, polymer loading rate. It was established experimentally that at Ј 0.1%, the destruction of the glassy polymer as a result of breaking the chemical bonds in the macromolecules of the printed polymeric tape material, namely polyvinyl chloride heat shrinkable tubular films, does not occur.

Figure 1 shows a printing machine, a general scheme; Fig. 2 is a diagram of the wiring of the material through the guide (section A-A in Fig. 1) before stretching the printed material; Fig. 3 is the same (section A-A in Fig. 1), after stretching the printed material.

The printed material 1 from the roll charging mechanism 2 through the braking device 3 enters the printing pair 4, containing the printing and printing cylinders 5 and 6, respectively, a passage along the guide 7, which covers both cylinders 5 and 6 on both sides and is installed with the possibility of returnable movement along the axis of the plate cylinder 5 (Fig. 2). After the printing pair 4, the material 1 is pulled by tread rubberized rollers 8 and 9 and enters the roll acceptance mechanism 10 driven by a direct current electric motor 11 through the friction clutch 12. The plate cylinder 5 and the drag roller 9 are driven by an electric motor 13 through the friction clutch 14. In this case, the roller 9 receives rotation from the shaft 15 of the forme cylinder 5 through the disagreeing gearbox 16 and chain transmissions consisting of sprockets 17-20 and chains 21 and 22.

The gearbox 16 contains gears 23-26, creating a gear ratio such that the frequency of rotation of shaft 27 is exceeded over the frequency of rotation of shaft 28 by an amount of 0.06-0.1%. The gear ratio can be changed using interchangeable pairs of gear wheels 25 and 26. The diameters of the plate cylinder 5 and roller 9 are the same, the pitch diameters of sprockets 18 and 19, 20 and 21 are the same, and therefore, when the press is operating, the tension of the material 1 in the area between the printing pair 4 and the long rollers 8 and 9 are due to the fact that the kinematic connection between

the plate cylinder 5 and the roller 9 in the form of a disagreeing gearbox 16 provide the difference between the linear speed of the roller 9 and the linear speed of the plate cylinder 5

printing pair 4, namely, the difference of the linear speeds of transportation of the tape through the pulling rollers and printing cylinders of the printing pair, equal to 0.06-0.1%. At the same time, the deformation of the stretch of the material 1, clamped by the pneumatic cylinders 29 and the ZO. Is 0.06-0.1%, in which the saber in the material 1 disappears and it becomes possible to maintain the edges of the material 1 relative to the plate cylinder 5.

5 Figure 2 shows the behavior of the printing material 1, which is that the printing material 1 has a tensile strain of less than 0.06%. This case is characterized by the fact that the subwoofer material 1 goes to the side, bending in zone a, limiting such movements with the help of guide 7. When trying in a known invention to displace material 1 with the help of guide 5, 7 in the direction of arrow B, respectively, lines b and 6i, between which the working zone of the plate cylinder 5 is located, containing printing elements (not shown), occurs in material 1

0 the formation of folds, which causes its deterioration. This is eliminated by stretching the material 1 by a value of 0.06-0.1% (FIG. 3), which is provided by the difference in the linear transport speeds of the tape

5 between tons of rollers 9 and between the forme cylinders 5 and 6 of the printing pair 4, equal to 0.06-0.1%, using a gear 16. As a result, material 1 is stretched by a specified amount at the proposed linear transport speed difference between The needles of the material 1 are repaired, which makes it possible to precisely adjust the edges of the material 1 in the printing pair 4 by moving the guide 7 so that the material 1 is evenly positioned relative to the working area. Bbch plate cylinder 5 (Fig.Z), which improves the quality of the printed material when posting the material through the printing machine.

Example. The proposed method is carried out on a printing press with

5 of the optimal difference in the speed of transportation of the tape between the pulleys and between the cylinders of the printing pair equal to 0.06% when sealing the polymeric tape material, namely, polyvinyl chloride heat-shrinkable sleeve

tapes - tubes TPT-C UMO 037.113.TU, 26.8 mm wide. The diameters of draw rollers are 108 mm, the diameter of the cylinders of the printing pair is 108 mm, the linear transport speed between the pulling rollers is 1.0006 m / s, the linear transport speed of the tape between the printing cylinders of the printing pair is 1 m / s, the distance between the axial rollers and the cylinders of the printing pair 7 m. The sealing polyvinylchloride heat shrinkable tube is continuously unwound from a cassette mounted on the roll charge mechanism and continuously passed through the cylinders of the printed pair. As a result, a print is made on the surface of the tube from a plate cylinder, which is partially immersed in an FSHV ink bath for flexographic printing. The tube is fed to the printing pair and wound onto the receiving cassette through a roll charging mechanism and a roll acceptance mechanism. After exiting the printing pair, the tube is stretched by knots placed in front of the roll acceptance mechanism. Thus, the material is stretched in the area between the printing pair and pulling rollers due to the difference in linear speeds of transporting the tape between pulling rollers on one side and between the cylinders of the printing pair on the other and 0.06%. The difference in tube transport speeds is provided by the gearbox. As a result, the print quality on the tube, namely, on the PVC heat-shrinkable tubular film is increased. At the same time, the print spread across the width of the tube is within ± 1.5 mm, the number of printed waste is 1%, material damage due to stretching of the material is not present.

PRI mme R 2. The proposed method is carried out on a printing press with

optimal difference in linear speeds of transportation of the tape between the pulleys and between the printing cylinders of the printing pair, equal to 0.1%, when sealing the polymer tape material, namely polyvinyl chloride heat-shrinking tubing. All other characteristics and parameters are the same as in example 1. As a result, a high quality sealable tube is obtained. At the same time, the print spread across the width of the tube is within ± .1 mm, the number of printed waste is 0.2%, material damage due to stretching of the material is not present.

Froze The proposed method is carried out on a printing press with an optimum difference in linear speeds of transporting the tape between pulling rollers and between the printing cylinders of the printing pair, equal to 0.08%, when sealing a polymeric tape material, namely a polyvinyl chloride heat shrinkable tubing. All other characteristics and parameters are the same as in example 1. As a result, a high quality sealable tube is obtained. At the same time, the print spread across the width of the tube is within 1.2 mm, the number of printed waste is 0.7%, and the material is not damaged due to stretching of the material.

Claims (1)

Claims The method of controlling the tension of a tape material in a printing machine, which consists in transporting the tape between pulling rollers at a faster speed than between the cylinders of the printing pair, characterized in that, in order to improve the print quality on a PVC heat-shrinkable tubular film, the tape is transported between tons with the use of rollers with a speed that is 0.06-0.1% higher than the transportation of the belt between the cylinders of the printing pair. LUJLLl - MfflI k /} Ј xy L JL 21 / s ts1- Ur g /  / /{--/one