GB1587497A

GB1587497A - Apparatus for drying a coated web of material

Info

Publication number: GB1587497A
Application number: GB22488/78A
Authority: GB
Original assignee: Polygraph Leipzig Kombinat Veb
Current assignee: Polygraph Leipzig Kombinat Veb
Priority date: 1977-06-02
Filing date: 1978-05-25
Publication date: 1981-04-08
Also published as: DD132005A1; DE2818832A1; SU906723A1; FR2392818A1; FR2392818B1; DE2818832C2; SE436852B; SE7806531L

Description

(54) APPARATUS FOR DRYING A COATED WEB OF MATERIAL (71) We, VEB KOMBINAT POLYGRAPH 'WERNER LAMBERZ' LEIPZIG, formerley VEB POLYGRAPH LEIPZIG Kombinat fur polygraphische Maschinen und Ausrüstungen, of 705 Leipzig, Zweinaundorfer Strasse 59, German Democratic Republic, a corporation organised under the laws of the German Democratic Republic do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an apparatus for drying a coated web of material.

The coated web may be dried in a drier by radiation such as infrared or ultraviolet radiation and cooled in a cooling unit connected downstream of the drier.

The drying of a printed or coated web in known driers is performed by infrared or ultraviolet radiators in that the web coming from the last printing unit is guided through an inlet gap into the drier, past the radiators and through an outlet gap out of the drier into a cooling unit. The guidance of the web from the printing unit to the cooling unit is freely floating in order to avoid the smearing of the print.

According to the kind of the printing and thereby the properties of the printing ink, the web is entrained by the first form or perfecting form printing cylinder by a certain looping angle before it detaches from the respective cylinder so that it does not always run into the drier at the level of the running plane of the web, but above or below the plane in dependence on the looping angle. This can also periodically alternate, whereby the web gets into oscillations perpendicularly to its conveying direction. This in turn means that the size of the inlet gap height must be dimensioned in accordance with the maximum looping amplitude to be expected. Through the relatively large inlet gap height, an uncontrollably large quantity of infrared or ultraviolet rays can penetrate outwardly. Also a directed air current, which is generated within the drier by means of a blower for the adequate cooling of the radiators, is impaired since an appreciable, and uncontrolledly large quantity of air is sucked in through the inlet gap, which in turn forces an increase in the blower performance. Altogether, the efficiency of the drier is worsened through these disadvantages to a degree that local smearing of the print is not excluded. It is also not insignificant that operating personnel are endangered by the ultraviolet radiation.

BRD-GM 7 228 906, discloses means for counter-acting these disadvantages by arranging a respective hood, a respective hood, a socalled tunnel, upstream of the inlet gap and the outlet gap. Each tunnel is provided with metal labyrinth plates. Although the output penetration of rays is somewhat reduced by these hoods and the non-adjustable metal labyrinth plates, the size of the inlet gap height of the hood must in the case of this drier be dimensioned in accordance with the greatest amplitude of the web oscillation by reason of the adhesion of the web to the first form or perfecting form printing cylinder. Thus, the uncontrolled suction of secondary air is effective to the same degree so that the intended efficiency of this drier is appreciably reduced and particularly the quality of the print of the last printing unit is impaired.

According to the present invention there is provided an apparatus for drying a coated web of material, comprising two plate members disposed respectively above and below a web path defined in the apparatus and each pivotable about a respective axis to converge towards each other in the direction of travel of the web to therebetween provide, downstream of the pivot axes, the drying apparatus with an inlet of selectably variable sizes. These two plate members, which are adjustable towards and locatable relative to the web, make a variation of the size of the inlet gap height possible in accordance with the looping angle on a first form and/ or perfecting form printing cylinder according to the kind of printing ink and thereby to the amplitude of the web. Thus, the size of the inlet gap height can always be set to a minimum without the web touching the plate members on oscillations arising and impairing the quality of the print. Since the plate members are pivotable independently of each other, the gap centre can readily be set in deviation from the running plane of the web. Furthermore, only an insignificant part of the rays generated in the apparatus can pass into the open. In consequence of the inlet gap height always being set to the minimum size, the air current in the dryer necessary for the cooling of the radiators is effected to the intended degree, because the air sucked in through the inlet gap has a defined volume. The sum of these advantageous effects according to the invention signifies the optimisation of the efficiency of the apparatus.

The plate members may be arched in such a manner that the arches are facing the running plane of the web. Air may be sucked in through the inlet gap by blower devices to hold the web constantly in suspension between both plate members. The air cushion, existing to both sides between the plate members and the web, makes an extremely small dimensioning of the inlet gap height possible, since it moreover strongly damps oscillations of the web perpendicularly to its surface.

Upstream of the plate members in conveying direction and between the pivot axes of the plate members and the associated upper or lower web surface may be arranged pivotable jet pipes which are selectably loaded individually or in common with air or settable pressure.

Thereby, an air cushion damping the web oscillations is built up between the plate members and the web, which facilitates the setting of a minimum inlet gap size between the plate members.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Figure 1 shows, in section, a drier with units connected immediately upstream and downstream of the drier.

Figure 2 shows, schematically, an inlet gap of the drier, with trapezoidally arranged metal guide plates.

Figure 3 shows, schematically, an inlet gap of the drier, with arched metal guide plates.

Figure 4 shows, schematically, an inlet gap similar to that shown in Figure 3 but acted upon by jets, and Figure 5 shows part of the drier in side elevation.

Referring now to the accompanying drawings, Figure 1 shows a printing unit 2 connected upstream and a cooling unit 3 connected downstream of a drier 1 in a web conveying direction. A web 4 of material to be printed on runs between upper and lower blanket cylinders 5 and 6 into the drier 1 and freely floating up to the cooling unit 3.

The drier 1 comprises an upper part 7 and a lower part 8, in which the radiators 9 are disposed and separated from one another in the web running plane 10. A laterally closed inlet hood 12, divided at the level of the web running plane 10 and fastened to the upper part 7 and the lower part 8, is arranged upstream of the inlet gap 11 of the drier 1. Metal guide plates 14 are pivotably mounted to a respective axle 13 in both parts of the inlet hood 12. As is shown in Figures 2 to 4, the metal guide plates 14 form an orifice relative to the plane of the web and to each other in the web running direction and provide a functionally effective inlet gap 15. To enable the metal guide plates 14 to be adjusted in correspondence with the oblique running of the web, which results from the adhesion of the web 4 to one of the two blanket cylinders 5 or 6 by a certain looping angle, a respective clamping screw 17 guided in a setting slot 16 is arranged at the inlet hood 12. The maximum expected inlet inclination of the web 4 determines the size of the opening of the inlet gap 15 in the inlet hood 12, which is upwardly tiltable. As is shown in Figure 5, one of the side walls 18 of the inlet hood 12 at its outer edge above and below the web running plane 10 has a scale 19, with the aid of which the deviation of the web 4 from the web running plane 10 is ascertainable and in correspondence with which the setting angle of the metal guide plates 14 can be set by means of the clamping screws 17. For this purpose, the setting slot 16 is likewise provided with a scale 20. The printed web is thus prevented from coming into contact with the inlet hood 12 or with the metal guide plate 14 and smearing the print. The setting of the metal guide plates 14 can be checked through a window 21 absorbing the ultraviolet radiation.

An arrangement ofjet pipes 22 at both sides of the web 4 immediately upstream of the metal guide plates 14 may be provided. These are selectably loadable individually or in common with air of settable pressure. Web oscillations are damped by the built-up air cushion so that the height of the actually effective inlet gap 15 formed by the metal guide plates 14 can be set to a minimum by means of the clamping screw 17.

The embodiments of the present invention described above by way of example have the advantage that by being able to vary the size of the inlet gap height, the intended flow conditions within the drier and thereby the efficiency thereof are not impaired so that a reduction in the quality, particularly of the print coming from the printing unit connected immediately in front of the drier, is excluded.

WHAT WE CLAIM IS: 1. An apparatus for drying a coated web of material, comprising two plate members disposed respectively above and below a web path defined in the apparatus and each pivotable about a respective axis to converge towards each other in the direction of travel of the web to therebetween provide, downstream of the pivot axes, the drying apparatus with an inlet of selectably variable size.

2. An apparatus as claimed in claim 1, comprising a hood surrounding the plate members.

3. An apparatus as claimed in either claim 1 or claim 2, wherein each plate member comprises a planar portion facing the web path.

4. An apparatus as claimed in any one of the preceding claims, wherein each plate member has at least a portion thereof which is convex towards the other plate member.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

is effected to the intended degree, because the air sucked in through the inlet gap has a defined volume. The sum of these advantageous effects according to the invention signifies the optimisation of the efficiency of the apparatus.

The plate members may be arched in such a manner that the arches are facing the running plane of the web. Air may be sucked in through the inlet gap by blower devices to hold the web constantly in suspension between both plate members. The air cushion, existing to both sides between the plate members and the web, makes an extremely small dimensioning of the inlet gap height possible, since it moreover strongly damps oscillations of the web perpendicularly to its surface.

Upstream of the plate members in conveying direction and between the pivot axes of the plate members and the associated upper or lower web surface may be arranged pivotable jet pipes which are selectably loaded individually or in common with air or settable pressure.

Thereby, an air cushion damping the web oscillations is built up between the plate members and the web, which facilitates the setting of a minimum inlet gap size between the plate members.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Figure 1 shows, in section, a drier with units connected immediately upstream and downstream of the drier.

Figure 2 shows, schematically, an inlet gap of the drier, with trapezoidally arranged metal guide plates.

Figure 3 shows, schematically, an inlet gap of the drier, with arched metal guide plates.

Figure 4 shows, schematically, an inlet gap similar to that shown in Figure 3 but acted upon by jets, and Figure 5 shows part of the drier in side elevation.

Referring now to the accompanying drawings, Figure 1 shows a printing unit 2 connected upstream and a cooling unit 3 connected downstream of a drier 1 in a web conveying direction. A web 4 of material to be printed on runs between upper and lower blanket cylinders

5 and 6 into the drier 1 and freely floating up to the cooling unit 3.

The drier 1 comprises an upper part 7 and a lower part 8, in which the radiators 9 are disposed and separated from one another in the web running plane 10. A laterally closed inlet hood 12, divided at the level of the web running plane 10 and fastened to the upper part

7 and the lower part 8, is arranged upstream of the inlet gap 11 of the drier 1. Metal guide plates 14 are pivotably mounted to a respective axle 13 in both parts of the inlet hood 12. As is shown in Figures 2 to 4, the metal guide plates

14 form an orifice relative to the plane of the web and to each other in the web running direction and provide a functionally effective inlet gap 15. To enable the metal guide plates 14 to be adjusted in correspondence with the oblique running of the web, which results from the adhesion of the web 4 to one of the two blanket cylinders 5 or 6 by a certain looping angle, a respective clamping screw 17 guided in a setting slot 16 is arranged at the inlet hood 12. The maximum expected inlet inclination of the web 4 determines the size of the opening of the inlet gap 15 in the inlet hood 12, which is upwardly tiltable. As is shown in Figure 5, one of the side walls 18 of the inlet hood 12 at its outer edge above and below the web running plane 10 has a scale 19, with the aid of which the deviation of the web 4 from the web running plane 10 is ascertainable and in correspondence with which the setting angle of the metal guide plates 14 can be set by means of the clamping screws 17. For this purpose, the setting slot 16 is likewise provided with a scale 20. The printed web is thus prevented from coming into contact with the inlet hood 12 or with the metal guide plate 14 and smearing the print. The setting of the metal guide plates 14 can be checked through a window 21 absorbing the ultraviolet radiation.

An arrangement ofjet pipes 22 at both sides of the web 4 immediately upstream of the metal guide plates 14 may be provided. These are selectably loadable individually or in common with air of settable pressure. Web oscillations are damped by the built-up air cushion so that the height of the actually effective inlet gap 15 formed by the metal guide plates 14 can be set to a minimum by means of the clamping screw 17.

The embodiments of the present invention described above by way of example have the advantage that by being able to vary the size of the inlet gap height, the intended flow conditions within the drier and thereby the efficiency thereof are not impaired so that a reduction in the quality, particularly of the print coming from the printing unit connected immediately in front of the drier, is excluded.

WHAT WE CLAIM IS: 1. An apparatus for drying a coated web of material, comprising two plate members disposed respectively above and below a web path defined in the apparatus and each pivotable about a respective axis to converge towards each other in the direction of travel of the web to therebetween provide, downstream of the pivot axes, the drying apparatus with an inlet of selectably variable size.
2. An apparatus as claimed in claim 1, comprising a hood surrounding the plate members.
3. An apparatus as claimed in either claim

1 or claim 2, wherein each plate member comprises a planar portion facing the web path.
4. An apparatus as claimed in any one of the preceding claims, wherein each plate member has at least a portion thereof which is convex towards the other plate member.
5. An apparatus as claimed in any one of

the preceding claims, comprising pivotable air blowing devices which are disposed respectively above and below the web path and upstream of the plate members and which are selectably operable individually or in common.
6. An apparatus for drying a coated web of material, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.
7. An apparatus as claimed in claim 6 and modified substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
8. An apparatus as claimed in claim 6 and modified substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.
9. An apparatus as claimed in claim 6 and modified substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.
10. An apparatus as claimed in any one of claims 6 to 9 and modified substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.