JP4613033B2 - Drying equipment - Google Patents

Description

  The present invention relates to a drying apparatus for drying water-based ink applied to a sheet material in a printing unit of a gravure printing machine.

  In recent years, water-based inks have been used instead of organic solvent type inks for the purpose of environmental conservation, etc., but when this water-based ink is dried, the amount of heat is much higher than that of organic solvent type inks. It is necessary, and if the temperature of the hot air blown to the sheet material is increased in order to secure this amount of heat, it is inevitable that the sheet material is heated to a high temperature and greatly expanded. When the sheet material undergoes large thermal expansion in this way, when color printing is performed by sequentially applying a plurality of colors of water-based inks, misregistration that shifts the application position of each water-based ink may occur, or the sheet material may be damaged. There is a problem that is easily formed.

In order to prevent the above disadvantages, as shown in Patent Document 1, hot air supply means for supplying hot air into a dryer attached to a gravure printing machine, etc., and the surface temperature of the sheet material carried out of the dryer And a heat quantity control for controlling the amount of hot air supplied from the hot air supply means based on a deviation between the surface temperature of the sheet material detected by the temperature detection means and a preset reference temperature. In order to maintain the surface temperature of the sheet material at a constant value, a heat amount control by the heat amount control means is executed using a drying apparatus provided with a means.
JP 2001-246306 A

  As disclosed in Patent Document 1, the amount of hot air supplied from the hot air supply means is controlled based on the detection value of the temperature detection means including a non-contact temperature sensor that detects the surface temperature of the sheet material. When it is configured to maintain the surface temperature of the sheet material at a constant value, it is difficult to accurately detect the temperature change of the sheet material by the temperature detecting means, so when performing color printing However, there is a problem that the occurrence of misregistration cannot be effectively prevented.

  That is, since water-based ink is partially applied to the uneven position of the sheet material, and the application position of the water-based ink on the sheet material generally varies according to the change of the printing pattern, Patent Document 1 With the disclosed temperature detecting means including a non-contact type temperature sensor or the like, it is difficult to accurately detect the temperature of the necessary portion of the sheet material (temperature at the ink application position). In order to accurately detect the temperature of the ink application position, it may be possible to move the temperature detecting means in response to a change in the print pattern, but in this case, the structure of the apparatus becomes complicated, There is a drawback that the temperature at the ink application position cannot be accurately detected unless the print pattern of the sheet material is accurately measured and input.

  Therefore, when color printing is performed by applying a plurality of water-based inks on top of each other, it is not possible to effectively prevent the application position of each water-based ink from shifting, and printing in which the conveyance speed of the sheet material changes. There is a problem that a large amount of defective products is generated due to the occurrence of the misregistration at the start or the like. This is because at the start of printing, as shown in FIG. 6, while maintaining the sheet material conveyance speed V at a low registration speed V1 (for example, about 30 m / min) for a certain period of time from the printing start time T0, each color. After initial registration is performed based on the alignment mark attached to the sheet material every time, the sheet material conveyance speed V is constant at a high speed (for example, about 150 m / min) at time T1 when the initial registration is completed. The printing speed is increased to V2. When the speed rises, if the temperature Wt of the hot air supplied from the hot air supply means into the dryer is set to a constant value, for example, about 60 ° C., the amount of heat of the hot air supplied per unit area of the sheet material gradually decreases. As a result, the temperature St of the sheet material gradually decreases as shown by the broken line in FIG.

  In order to prevent the occurrence of misregistration due to a decrease in the temperature St of the sheet material, that is, the displacement of the printing position due to the variation in the expansion amount of the sheet material, as shown in Patent Document 1, temperature detection is performed. Even if it is configured to detect the temperature change of the sheet material by means and execute the control to adjust the temperature Wt of the hot air, it is difficult to accurately detect the temperature change of a necessary portion on the sheet material, There is a drawback that a predetermined time is required until the temperature Wt of the sheet material reaches an appropriate value, and a large amount of defective products due to the misregistration are generated during this time.

  In addition, in order to suppress the occurrence of misregistration due to large fluctuations in the thermal expansion amount of the sheet material, it is possible to reduce the temperature of the hot air and slow down the sheet material conveyance speed. However, there is a problem that the printing speed is lowered and the working efficiency is deteriorated. For this reason, it has been desired that generation of defective products due to misregistration can be effectively suppressed at the start of printing or the like when the sheet material conveyance speed is changed without reducing the printing speed.

  The present invention has been made in view of the above points, and can suppress the generation of defective products due to misregistration at the start of printing in which the conveyance speed of the sheet material changes without reducing the printing speed. Another object of the present invention is to provide a drying apparatus capable of quickly and appropriately drying water-based ink applied to a sheet material with a simple configuration.

The invention according to claim 1 is a dryer for carrying in a sheet material printed by applying a water-based ink in a printing unit of a gravure printing machine, and for drying the water-based ink applied to the sheet material. Based on the hot air supply means for supplying hot air into the dryer, the tension detection means for detecting the tension of the sheet material carried into the dryer, and the tension of the sheet material detected by the tension detection means , Temperature control means for controlling the temperature of the sheet material so as to make the tension coincide with a preset reference tension .

  According to a second aspect of the present invention, there is provided the drying apparatus according to the first aspect, wherein the temperature control means is configured such that the sheet material detected by the tension detection means is lower than a preset reference tension. The temperature of the sheet material is lowered by operating a cold air supply means for cooling the sheet.

  According to a third aspect of the present invention, in the drying apparatus according to the first aspect, the temperature control means supplies hot air according to a deviation between the tension of the sheet material detected by the tension detection means and a preset reference tension. The temperature of the sheet material is controlled by adjusting the amount of hot air supplied from the means into the dryer.

  According to the first aspect of the present invention, the sheet material conveyance speed increases at the start of printing when the sheet material conveyance speed changes from a low registration speed to a high steady printing speed, and the temperature of the sheet material increases. When the tension of the sheet material fluctuates in response to this change, the tension fluctuation is immediately detected by the tension detection means, and the temperature control of the sheet material is executed by the temperature control means. The generation of defective products due to the deviation can be effectively suppressed, and the water-based ink applied to the sheet material can be dried quickly and appropriately.

  According to the second aspect of the present invention, when the temperature of the sheet material rises and the amount of expansion increases, and the corresponding tension of the sheet material becomes lower than the reference tension, Since the decrease is immediately detected and the control for lowering the temperature of the sheet material is executed by the cold air supply means, there is an advantage that it is possible to effectively prevent the occurrence of defective products due to the displacement of the printing position.

  According to the third aspect of the present invention, when the temperature of the sheet material changes and the tension of the sheet material fluctuates correspondingly, the fluctuation of the tension is immediately detected and the hot air supply means Since the temperature of the sheet material is controlled by adjusting the amount of hot air supplied from the air to the dryer, there is an advantage that it is possible to effectively prevent the occurrence of defective products due to the displacement of the printing position. is there.

  FIG. 1 shows a schematic configuration of a gravure printing machine 1 provided with a drying apparatus according to the present invention. The gravure printing machine 1 is configured to feed a sheet material 3 from a sheet roll 2 around which a sheet material 3 to be printed is wound, and to apply a predetermined tension to the sheet material 3 fed from the feeding unit 4. An infeed unit 7 that supplies the preheater 6, a plurality of printing units 8 to 10 that perform color printing by sequentially applying a plurality of colors of water-based ink to the sheet material 3 derived from the preheater 6, An outfeed unit 11 that pulls out the sheet material 3 by applying a predetermined tension, and a winding unit 12 that winds up the printed sheet material 3 drawn out by the outfeed unit 11 are provided.

  Each of the printing units 8 to 10 includes a printing plate cylinder 14 that is rotationally driven by a drive motor 13 and is coated with water-based ink on a peripheral surface thereof, and a pressure roller 15 that presses the sheet material 3 against the printing plate cylinder 14. And a drying device 17 for drying the water-based ink applied to the sheet material 3 in the printing unit 16. Further, between the printing units 8 and 9 and between the printing units 9 and 10, a plurality of water-based inks are sequentially applied to the sheet material 3 in the printing unit 16 of each printing unit 8 to 10. In addition, a compensator roll 18 is provided for correcting misalignment of printing positions (register misregistration).

  As shown in FIGS. 2 and 3, the drying device 17 includes a dryer 21 composed of a box-shaped casing having a carry-in port 19 and a carry-out port 20 for the sheet material 3, and is arranged in the dryer 21 at predetermined intervals. A plurality of guide rollers 22 provided, a hot air blowing section 23 for blowing hot air for drying toward the surface (water-based ink application surface) of the sheet material 3 guided by the guide rollers 22, and the sheet material 3 A cold air blowing unit 24 is provided on the back surface side and blows out cold air for cooling each guide roller 22. The guide rollers 22 are arranged at a predetermined interval so as to form a curved sheet path between the carry-in port 19 and the carry-out port 20 of the sheet material 3. The sheet material 3 introduced from the printing unit 16 into the dryer 21 moves upward while being guided by the guide roller 22 and is led out from the carry-out port 20.

  On the wall surface of the dryer 21, an air supply duct 26 connected to a hot air supply means 25 having a blower and a heating source (not shown) is installed on the downstream side in the sheet conveying direction, and exhaust air (not shown). An exhaust duct 27 communicating with the processing unit or the like is installed on the back side of the air supply duct 26. The air supply duct 26 is connected to a side wall surface of a header 28 having a constant width extending in the conveying direction of the sheet material 3. The header 28 is provided with a hot air blowing portion 23 for drying that extends in a direction orthogonal to the conveying direction of the sheet material 3.

  The hot air blowing section 23 includes three first hot air blowing sections 23 a composed of V-shaped nozzles arranged in the vicinity of the carry-in port 19 for the sheet material 3, and V provided in the vicinity of the carry-out port 20 for the sheet material 3. Perforated plate having a single second hot air blowing portion 23b composed of a mold nozzle and a large number of drying air blowing holes 29 disposed between the first hot air blowing portion 23a and the second hot air blowing portion 23b. It is comprised by the six 3rd hot air blowing parts 23c which consist of nozzles.

  The first to third hot air blowing portions 23a to 23c are respectively disposed at positions facing the guide roller 22, and are detachably attached to the header 21 with attachment bolts or the like. The hot air outlets 23a to 23c are disposed at predetermined intervals, so that the drying air blown from the hot air outlets 23a to 23c is exhausted from the installation side of the exhaust duct 27. A gap 39 is provided between the adjacent hot air blowing parts 23. The gap 39 has a dimension that can smoothly guide the exhaust of the drying air, and is set to a dimension that can prevent the dryer 21 from becoming unnecessarily large. Further, the exhaust duct 27 is disposed in the upper part of the dryer 21 in substantially the entire width direction thereof.

  And when starting the said gravure printing machine 1, the water source applied to the said sheet | seat material 3 at the time of regular printing can be dried appropriately by making the heating source of the said hot air supply means 25 and an air blower into an operating state. The hot air having a constant temperature set in such a manner is supplied from the hot air blowing sections 23 into the dryer 21 and blown onto the surface of the sheet material 3 with a constant air volume, and is formed on the front and bottom surfaces of the exhaust duct 27. Further, the exhaust of the drying air introduced into the exhaust duct 27 from the exhaust intake is led out to the outside.

  On the other hand, the cold air blowing part 24 is formed on a surface facing each guide roller 22 of the header 30 which is disposed between a pair of adjacent guide rollers 22 and 22 so as to extend in the axial direction thereof. The header 30 is connected with an intake duct 32 provided with a cool air supply means 31 having a blower. The guide roller 22 is cooled by blowing the cool air from the cold air blowing section 24 to the peripheral surfaces of the guide rollers 22 to cool the guide rollers 22. It is comprised so that the temperature of the sheet | seat material 3 which contacts may be reduced.

  Further, the drying device 17 is provided with a tension detecting means 33 for detecting the tension of the sheet material 3 led out from the carry-out port 20 of the dryer 21. The tension detecting means 33 includes a pickup roller 34 disposed along the conveying path of the sheet material 3 and a strain gauge type or inductance type tension sensor 35 provided on a rotation support portion of the pickup roller 34. Thus, when the sheet material 3 is conveyed, the tension acting on the sheet material 3 is detected by the tension sensor 35, and this detection signal is output to the control unit 36 described below.

  As shown in FIG. 4, the control unit 36 includes a storage unit 37 that stores a preset reference tension of the sheet material 3, that is, an optimum value of the tension that is applied during steady printing of the sheet material 3, and the tension detection unit 33. Temperature control means 38 for controlling the temperature of the sheet material 3 by outputting a control signal corresponding to the tension of the sheet material 3 detected by the tension sensor 35 to the blower 31a of the cold air supply means 31.

  The temperature control means 38 compares the detected tension value of the sheet material 3 with the reference tension read from the storage means 37, and when it is confirmed that the detected tension value is lower than the reference tension. The air blower 31a of the cold air supply means 31 is operated, and the air flow rate is adjusted to a value corresponding to the deviation between the detected tension value and the reference tension, whereby the sheet material 3 is cooled and the tension is set as a reference. Control is performed to match the tension. As a result, at the start of printing in which the conveyance speed of the sheet material 3 changes, the hot air set at the same temperature as that during steady printing of the sheet material 3 is supplied from the hot air supply means 25 into the dryer 21 at a constant air volume, Control is performed to maintain the temperature St of the material 3 substantially constant.

  As described above, the dryer 21 into which the sheet material 3 printed by applying the water-based ink is applied in the printing unit 16 of the gravure printing machine 1 and the water-based ink applied to the sheet material 3 are dried. The hot air supply means 25 for supplying the hot air into the dryer 21, the tension detection means 33 for detecting the tension of the sheet material 3 carried into the dryer 21, and the sheet material detected by the tension detection means 33 Since the temperature control means 38 for controlling the temperature of the sheet material 3 according to the tension 3 and the preset reference tension is provided, it is caused by misregistration at the start of printing when the conveyance speed of the sheet material 3 changes. The water-based ink applied to the sheet material 3 can be dried quickly and appropriately without causing the adverse effect of producing a large amount of defective products.

  That is, as shown in FIG. 5, the sheet material 3 is attached to the sheet material 3 for each color while maintaining the conveyance speed V of the sheet material 3 at a registration speed V1 of about 30 m / min for a certain time from the printing start time T0. When performing the initial registration based on the alignment mark (register mark), when hot air set at the same temperature Wt as that during steady printing of the sheet material 3 is supplied from the hot air supply means 25 into the dryer 21, The temperature St of the sheet material 3 is significantly higher than that during normal printing, and the amount of expansion of the sheet material 3 is extremely larger than that during normal printing. As a result, the tension acting on the sheet material 3 becomes lower than the reference tension, and this state is detected based on the detected value of the tension detecting means 33. Therefore, the fan 31a of the cold air supplying means 31 is operated to guide the tension. By blowing a large amount of cold air B onto the roller 22, control for lowering the temperature St of the sheet material 3 is executed, the temperature St of the sheet material 3 is maintained substantially constant, and the tension of the sheet material 3 is equal to the reference tension. Will be held equal.

  Then, at the time T1 when the initial registration is completed, the control for increasing the conveyance speed V of the sheet material 3 to the steady printing speed V2 set to a high speed of about 150 m / min is executed, whereby the sheet material 3 When the amount of heat of the hot air supplied per unit area gradually decreases and the temperature St of the sheet material 3 begins to decrease, the expansion amount of the sheet material 3 decreases at the same time, and the tension acting on the sheet material 3 increases. Therefore, this increase in tension can be instantaneously detected by the tension detection means 33. Therefore, the control for gradually decreasing the air volume B of the cold air blown from the cold air supply means 31 to the guide roller 22 is accurately executed according to the increase in the tension, and the temperature St of the sheet material 3 is maintained substantially constant. The occurrence of misregistration due to the decrease in the temperature St, that is, the deviation of the printing position due to the variation in the expansion amount of the sheet material 3 can be quickly and appropriately suppressed. For this reason, there is an advantage that it is possible to effectively prevent the generation of defective products due to the misregistration without taking measures such as reducing the printing speed.

  Moreover, even when the water-based ink is partially applied to the uneven position of the sheet material 3 and the application position moves according to the change of the printing pattern, the sheet corresponds to the temperature change of the sheet material 3. Since the tension of the material 3 fluctuates accurately, the sheet material 3 can be used without adopting a complicated configuration such as moving a temperature detecting means including a non-contact type temperature sensor in accordance with the change in the print pattern. It is possible to accurately and quickly detect the tension fluctuation corresponding to the temperature change, and to appropriately control the air volume B of the cold air.

  When the tension of the sheet material 3 detected by the tension detection means 33 is lower than a preset reference tension, the amount of hot air supplied from the hot air supply means 25 into the dryer 21 is kept constant. However, instead of the above-described embodiment configured to lower the temperature of the sheet material 3 by operating the cold air supply means 31 and blowing the cold air to the guide roller 22, the cold air is blown to the back surface of the sheet material 3. Thus, the sheet material 3 may be directly cooled. In addition, a coolant composed of cooling water or the like is supplied into the guide roller 22 and the supply amount of the coolant is controlled, so that the sheet material 3 is controlled according to the tension of the sheet material 3 detected by the tension detection means 33. The temperature St may be indirectly controlled.

  Furthermore, when the tension | tensile_strength of the sheet | seat material 3 detected by the said tension | tensile_strength detection means 33 is lower than the preset reference | standard tension | tensile_strength, it was comprised so that the temperature of the sheet | seat material 3 might be lowered by operating the cold wind supply means 31. Instead of the above embodiment, the temperature of the hot air supplied from the hot air supply means 25 into the dryer 21 in accordance with the deviation between the tension of the sheet material 3 detected by the tension detection means 33 and a preset reference tension. It is also possible to control the temperature of the sheet material 3 by adjusting. Further, both the supply amount of the cold air supplied from the cold air supply means 31 into the dryer 21 and the heat amount of the hot air supplied from the hot air supply means 25 to the dryer 21 are determined by the tension of the sheet material 3 and the reference tension. You may make it control the temperature of a sheet | seat material by controlling according to a deviation.

  As described above, the temperature of the hot air supplied from the hot air supply means 25 into the dryer 21 is adjusted in accordance with the deviation between the tension of the sheet material 3 detected by the tension detection means 33 and a preset reference tension. Thus, when the temperature of the sheet material 3 is controlled, the tension of the sheet material 3 detected by the tension detection means 33 is set in advance with a simple configuration without providing the cold air supply means 31. While having the advantage that the sheet material 3 can be kept constant according to the deviation from the reference tension, it is difficult to quickly change the temperature of the hot air. For this reason, it is inevitable that a time difference occurs between the time point when the tension is detected and the time point when the temperature control of the sheet material 3 is performed by the hot air, and a control hunting occurs according to the time difference. As shown in FIG. 6, a predetermined time is required until the sheet material 3 reaches an appropriate temperature, and a defective product may be generated due to misregistration during this time. Therefore, as shown in the above embodiment, when the tension of the sheet material 3 detected by the tension detection means 33 is lower than the preset reference tension, the cold air supply means 31 is operated to set the temperature of the sheet material 3. It is preferable to configure so as to decrease.

It is the schematic which shows the whole structure of a gravure printing machine. It is side surface sectional drawing which shows embodiment of the drying apparatus which concerns on this invention. It is front sectional drawing which shows the specific structure of a drying apparatus. It is a block diagram which shows the structure of a control unit. It is a time chart which shows the change state etc. of the surface temperature of a sheet material. It is a time chart which shows the change state etc. of the surface temperature of the sheet material in a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gravure printing machine 3 Sheet material 17 Drying device 21 Dryer 25 Hot air supply means 31 Cold air supply means 33 Tension detection means 38 Temperature control means

Claims (3)

A dryer that carries in the sheet material printed by applying the water-based ink in the printing section of the gravure printing machine, and hot air for drying the water-based ink applied to the sheet material is supplied into the dryer. A hot air supply means, a tension detection means for detecting the tension of the sheet material carried into the dryer, and a reference tension set in advance based on the tension of the sheet material detected by the tension detection means. And a temperature control means for controlling the temperature of the sheet material so as to match .   The temperature control means lowers the temperature of the sheet material by operating a cold air supply means for cooling the sheet material when the tension of the sheet material detected by the tension detection means is lower than a preset reference tension. The drying apparatus according to claim 1, wherein the drying apparatus is configured as described above.   The temperature control means adjusts the amount of heat of hot air supplied from the hot air supply means into the dryer according to a deviation between the tension of the sheet material detected by the tension detection means and a preset reference tension. The drying apparatus according to claim 1, wherein the drying apparatus is configured to control a temperature of the material.

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