JP3012359B2 - Apparatus for drying web and web dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION The present invention relates to a web support device, and more particularly to a web support and guide device for a web drying device, wherein the web moving in the longitudinal direction is the length of the web drying device. Floatingly supported and maintained in a straight path across (ie, centered about the longitudinal centerline of the web).

[0002] When drying a moving web such as paper, film, etc., it is desirable that the web be contactlessly supported during the drying operation to avoid damage to the web itself or the ink or coating on the web. One common arrangement for contactlessly supporting the web comprises upper and lower sets of air bars extending along a substantially horizontal extension of the web. Air emanating from the lower set of air bars floats and supports the web, and air emanating from the upper set of air bars maintains the web at a substantially constant distance from both sets of substantially straight air bars. To stabilize the web. The air blown from both sets of air bars is usually heated to promote web drying, and typically the air bar arrangement is slightly larger by exhaust blowers that draw in volatiles emanating from the web. In an enclosure maintained below atmospheric pressure.

[0003] Web dryers are used for photographic film and web
It is used in many printing and printing applications, such as offset printing, and other types of printing processes. In some applications, such as photographic film processing, often 150
Very long web dryers, even feet long, are commonly used. The greater the ratio of the length of the dryer to the width of the web (hereinafter referred to as the "length to width ratio"), the more the web will weave (crossing back and forth) or shift (center). (To move sideways from the line and stay there). In addition, thin plastic
Some webs, such as films, naturally lay in a "banana-shaped" curvature when laid flat, as in a dryer, thereby exacerbating web weaving and shifting problems. Web shifting and weaving also occur when web tension is low and when lightweight webs such as polyester films are used.

As the moving web exits the dryer, it is typically wound around one or more rotating winding members, such as a chill roll. As web weaving or shifting occurs as the web passes through the dryer, the web is shifted or woven accordingly as it contacts the rotating take-up member. If the web is not returned to a straight orientation relative to the centerline, the web will not wind properly and the press must stop. This results in expensive downtime and waste.

[0005] Other problems arise from web weaving or shifting, for example, if the web moves to one side or the other and stays in a new position, it will not be centered on the press and will not be rejected. Is generated. If the web weave or shift is severe enough, the web will tear or crack. These problems also result in press downs and, thus, precious production time losses.

[0006] In the past, attempts have been made to avoid web weaving and shifting by guiding the web using a contact system, such as a series of rollers. These systems are undesirable because they damage the ink or coating on the web, and are therefore inefficient in situations where there is a high length to width ratio.

Thus, at points in the dryer that tend to weave or shift as they move through the web dryer, it is desirable to provide a means for floating and supporting and driving the web in a substantially linear path.

SUMMARY OF THE INVENTION The problems of the prior art have been solved by the present invention for an apparatus for handling and guiding a running web. More particularly, the present invention relates to an apparatus for floatingly supporting a web and maintaining the web in a substantially straight path as it moves through the dryer. The invention further relates to a dryer provided with such a web handling and guiding device.

The web handling and guiding device of the present invention comprises:
i) one or more adjustable air bars, each having an elongate surface for releasing air, said surface being in opposing relation to the running web, and each having two ends One or more adjustable air bars; ii) air supply means in fluid communication with the air bar; iii) adjustable air such that the orientation of one or both surfaces is adjustable with respect to the running web. Adjusting means for changing the orientation of the elongated surface of the bar. In a preferred embodiment, each said surface is
It rotates about an axis substantially parallel to the longitudinal centerline of the running web. Additionally or alternatively, each said surface rotates about an axis substantially perpendicular to the longitudinal centerline of the running web. The steerable air bar assembly is positioned in the web dryer such that the web is guided through the dryer in a substantially straight path. One or more steerable air bar assemblies are used in the web dryer. The dryer also includes one or more fixed air bars.

[0010] In a preferred embodiment of the invention, the apparatus further comprises back-pressure means in combination with the steerable air bar assembly to create a counterforce to return the web to a substantially central position. . The back pressure means preferably comprises one or more rims, preferably arranged at or near the end of one or more fixed air bars in the web dryer.

In one embodiment of the invention, the air supply means of the steerable air bar device comprises a header at one end sealingly connected to a flexible air duct. The air bar allows air to flow from the air duct to the header,
And it is arranged adjacent to the header so that it flows from the header to the air bar.

In yet another embodiment of the invention, the adjustable air bar orientation has a jack located at one end of the air bar assembly and a pivot located between the two ends. And adjustment means comprising support means.

In a method aspect, the present invention relates to a method for guiding a web in a substantially straight path, for example when passing through a web dryer, using the apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION A web dryer for floating a running web is shown in FIG. FIG. 1 illustrates one type of web dryer in which the guide device of the invention is used. The apparatus comprises an elongate dryer housing 2 closed by a top 3, a bottom 4, one side 5 and an opposite side 6. The entrance end 7 is provided with a horizontal slot 8 for the web W to enter. The opposite outlet end is the end wall 10 and the web W
Is formed by the corresponding slot 11 from which the liquid is discharged. The dryer comprises an upper fixed air bar 15 and a lower fixed air bar 16, a header frame 26 supporting the fixed air bar and delivering and communicating air, upper and lower air supply ducts 20 and 22, and air. And a central air supply duct 28 that supplies the header. The upper and lower air bars are positioned across the web and, when the dryer is operating, staggered along the web such that the web W assumes a conventional sinusoidal shape, as shown in FIG. There is a relationship arranged at intervals.

To illustrate the invention, the web dryer shown in FIG. 1 is provided with two fixed air bars 18 each having two ends, at least one of each of the ends. With back pressure means disposed (shown in FIG. 2 and discussed below). The back pressure means serves to move the shifted web to a central position and is preferably at least in a fixed air bar located in the area of the dryer where the running web tends to shift. The back pressure means is preferably located about halfway along the length of the dryer, for example, in an air bar 15 feet from the entrance for a 30 foot long dryer. It will be appreciated that the desired number of air bars 15 and 16 are provided with back pressure means at the ends.

The steerable air bar of the invention (FIGS. 4 and 5)
(Shown in the figure) is schematically illustrated by the air bar 24 of FIG. These steerable air bars do not engage the header and upper and lower air ducts in a manner similar to the fixed air bar, but a flexible seal is provided between the standard header and the adjustable air bar assembly. As generated
As shown in FIG. 6 and discussed in detail below, it is separately connected to an extension of header 26 connected to the header by a sealing flange and a sealing gasket. As with the back pressure means, a steerable air bar assembly can be present in any number in the web dryer and can be substituted for any number of fixed air bars. In fact, all or a group of fixed upper and lower air bars are replaced by a single steerable air bar assembly with a similar number of steerable air bars. When it is desired to use a small number of steerable air bar assemblies, it is again desirable to place them at locations in the dryer where web shift is expected, such as the vertical center point of the dryer. It is. A fragmentary enlarged view of an air bar with back pressure means according to one embodiment of the invention is shown in FIG. The rim 34 is shown attached to the end 30 of the air bar 18. In the embodiment shown in FIG. 2, the rim is bolted to the end of the air bar, but any conventional method may be used to attach the rim, or it may be integral with the air bar. It is a target. The rim 34 is also partially due to the width of the web,
8 are located at various points along the surface. The rim is preferably a T-shaped member formed by an elongate member 35, as shown in FIG. 2, and in the embodiment shown extends substantially vertically on the surface 33 of the air bar 18. And is supported at this position by a support member 31. The support member 31 is attached to the air bar by any suitable means, such as a bolt 64 and an air bar mounting bracket 66, as shown in FIG. The weir members 35 are preferably provided with fins 17 at each of their ends so that the web does not tend to obstruct the ingress and egress of the weir. In one embodiment, the lower edge of the weir member 35 is adjustable and is raised from the surface 33 by the support member 31 such that the distance between the lower edge and the surface is about 5 cm to 60 cm. Vertical adjustment of the weir member 35 is achieved by allowing the leaked air to escape from under the rim.
Means are provided for controlling the back pressure. This embodiment typically has high nozzle speeds, e.g.
00-16,000 fpm and is used in applications that produce very high back pressure. In another embodiment of the invention, for use at lower nozzle speeds, the weir member 35 is stationary and the lower rim approaches or contacts the surface of the air bar. In this embodiment, it is generally preferred that the lower edge of the weir member be in intimate sealing contact with the surface of the air bar. The weir member 35 with the fins 17 is also preferably long such that each end of the elongate member is substantially aligned with the corresponding air bar slot 32.

While this arrangement is preferred for edging, any means of creating back pressure against the web edges is used when an air bar is used. This phenomenon is schematically illustrated in FIG. In frame 1, one edge of web W approaches edge 34 during web weaving as the web passes over air bar 30. In frame 2, edging 34 creates a back pressure against web W, driving it towards the initial path in frame 3. The back pressure means also preferably can provide mechanical resistance to the web if air back pressure is found to be insufficient to return the web to the path. Thus, if the web continues to move toward rim 34 in frame 2, it will ultimately physically contact the rim and be returned to the initial path.

The back pressure means is disposed at one or both ends of the air bar. In general, it is usually difficult to predict in which direction the web will shift as it moves through the dryer, so the back pressure means is preferably located at both ends of the air bar. However, if the direction of the web shift is known, the back pressure means is only located at the end of the air bar where the web shifts.

A perspective view of a steerable air bar assembly 24 according to one embodiment of the invention is shown in FIG. In this embodiment, the assembly includes upper and lower headers 44.
And 42 and includes three adjustable air bars 38 for containing and communicating with the air. (The combination of two lower air bars and lower headers and a single upper air bar and upper header 44 is hereinafter referred to as a lower and upper air bar / header assembly, respectively.) The header assembly includes a header carriage 36 and a support member 5.
0 and are maintained in opposing spaced relation by spacer means having an upper and lower header 4.
4 and 42 are each sealingly connected at one of their ends to upper and lower flexible air ducts 46 and 48, respectively. The header carriage 36 is connected to the screw jack 40 at the lower edge, and the lower air bar / header assembly engages a pivot bearing 52 on each side,
It is supported by the support member 54 using the connecting rod 53.
Thus, when the screw jack 40 is adjusted up and down, the ends of both air bar / header assemblies adjacent to the screw jack 40 will be correspondingly raised and lowered as shown schematically in FIG. Moving. Angle adjustment of the air bar / header assembly is thus facilitated by pivot support means including pivot bearings 52 and connecting rods 53 and angle adjustment means including screw jacks 40 for translation or rotational movement in other planes. While rotating the air bar / header assembly about an axis A substantially parallel to the longitudinal centerline of the running web. The presence of the header carriage 36 and the support member 50 causes this movement without altering the spatial relationship between the air bars. Simultaneous adjustment of the orientation of both the upper and lower air bars is further facilitated by the flexible air ducts 46 and 48, regardless of the position of the header, the sealing relationship between the upper and lower headers 44 and 42 and the air supply. To maintain.
One type of flexible air duct used in the invention is described in U.S. Pat. No. 4,480,859, which is incorporated herein by reference.

A preferred form of the steerable air bar assembly of the invention is shown in FIGS. However, in broad terms, the invention relates to i) a plurality of adjustable air bars, each having an elongating surface that emits air, said surface being in opposing relation to the running web, and each having A plurality of adjustable air bars with two ends; ii)
A steerable air bar assembly comprising: an air supply means in fluid communication with the air bar; and iii) adjusting means for changing the orientation of one or both of the elongate surfaces of the air bar adjustable with respect to the traveling web. Pointed. In a preferred embodiment, one or both of the elongate surfaces is adjusted so that one or both of the surfaces rotate about an axis substantially parallel to the longitudinal centerline of the running web. Alternatively or additionally, the elongate surface rotates about an axis substantially perpendicular to the longitudinal centerline of the running web. In an alternative embodiment of the invention, the adjusting means comprises other angle adjusting means and pivoting support means, such as cables, rod-mounted pneumatic cylinders, and other conventional means for providing adjustable movement. I do. Additionally, in some applications, it is desirable to individually adjust the orientation of the upper and lower air bar / header assemblies. In these applications, the steerable air bar assembly does not include spacing means, such as the header carriage and support means described above. Spacing means are thus eliminated, and separate adjusting means are provided for the upper and lower air bars /
A header is provided for each of the header assemblies. In some cases, the air bar / header assembly is such that each pair of air bar / header assemblies has a total of four adjustable points.
Adjustment means are provided at each of the ends, as well as in both the upper and lower assemblies.

Adjustment of the orientation of the air bar surface by the adjusting means may be accomplished manually by the dryer operator, under computer logic control, or by other means.

In yet another embodiment of the invention, the steerable air bar assembly further comprises back pressure means, as described above. The use of back pressure means on a steerable air bar in a dryer is an addition or alternative to the use in a fixed air bar as described above. The air supply means may alternatively comprise a plurality of headers, as shown in FIG. 6, each header having a standard header air supply duct 26 with a sealing gasket 56 at one end. For example, a conventional header feed duct used to feed other feed bars in a dryer) and an extension 6 to an air feed duct.
0 and a sealing flange 62 disposed between the extension and the sealing gasket so that air delivery is maintained during angular adjustment of the air bar / head assembly. As shown in FIG. 6, the adjustable air bar 18 contains and communicates air with the extension 60, while the fixed air bar 16 contains and communicates air with the standard header air duct 26. I do. Additionally, other spacing means may be used in place of the header carriage 36 if a fixed spatial relationship is maintained between the upper and lower air bars. This type of air supply is often preferred and generally required in a dryer as shown in FIG.

[0023] Any type of air bar can be used in the present invention. A preferred type of air bar is disclosed in U.S. Patent Nos. 3,549,070, 3,873, referenced herein.
No. 013 and 3,964,656. Further, a desired number, for example, 50 or more air bars are used in the air bar / head assembly.

[0024] The steerable air bar assembly of the invention is assembled using conventional methods, as described in US Patent No. 3,776,440 referenced herein.

In practice, the position of the running web edge is monitored at one or more locations in the dryer using conventional sensing means, such as fiber optics. Based on these measurements of the position of the web edge, the steerable air bar is adjusted periodically or continuously to provide a force that adjusts the web to a substantially straight path. Alternatively, instead of detecting the position of the web as it travels through the dryer, computer generated data may be used to predetermine the desired web path and predicted web position and to compare these two positions. used. The steerable air bar is then adjusted based on the comparison to adjust the position of the web to the desired web path. As mentioned above, the back pressure means is disposed on the fixed or steerable air bar at the location where the web is expected to be woven or drifted. This is also experimentally
For example, determined by performing a dry run before running a given web through a dryer, or by using computer generated data.

Thus, in a method aspect, the invention relates to a method of guiding a web in a substantially straight path, for example, as the web passes through a web dryer. The method is responsive to driving the web through a dryer, floating and supporting the web, detecting a position of a web edge, and adjusting the position of the web. Providing force. In an alternative embodiment of the invention, the method includes predicting the location of the web based on computer-generated or experimental data rather than detecting the location. The adjustment power is
It may be provided by one or more steerable air bars, back pressure means, or a combination thereof. While the preferred embodiment of the invention has been described, other variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view taken along the length of a web drying device including a device for handling and guiding the web according to one embodiment of the invention.

FIG. 2 is a fragmentary enlarged perspective view of an air bar including an edging.

FIG. 3 is a schematic diagram showing the mechanism by which the rim reduces web drift.

FIG. 4 is a perspective view of a steerable air bar assembly according to one embodiment of the invention.

FIG. 5 is a front view of the device of the steerable air bar assembly showing air bar steering.

FIG. 6 is a side view of an alternative air supply means.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-125508 (JP, A) JP-A-50-61754 (JP, A) JP-B-53-4666 (JP, B2) US Patent 3,776,440 (US U.S. Pat. No. 3,873,013 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 20 / 10,23 / 24 F26B 13/20

Claims (19)

(57) [Claims] (1) Guide the web along a substantially straight path
Equipment that dries the web while floating
hand, a) Upper header and web positioned above web
A lower header positioned below b) one or more adjustable air bars, each with
Has two ends and an elongate surface to release air,
The surface is in facing relationship with the web and one of the headers
One or more keys in communication with
Adjustable air bar, c) communicating with the header to supply air to the air bar;
Air supply means for d) changing the orientation of one or both headers relative to the web
By adjusting the air bar against the web
Adjusting means for changing the orientation of the elongated surface.
An apparatus characterized in that: (2) The orientation of the elongate surfaces is such that each surface is a web
To rotate about an axis substantially parallel to the vertical centerline of the
An apparatus according to claim 1, wherein the apparatus is arranged. (3) The orientation of the elongate surfaces is such that each surface is a web
To rotate about an axis substantially perpendicular to the vertical centerline of the
An apparatus according to claim 1, wherein the apparatus is arranged. (4) The air supply means includes a plurality of headers,
A flexible duct sealingly connected to each
Apparatus according to claim 1 provided. (5) Air supply means having a plurality of headers
Each header has a sealing gasket at one end.
To standard header air supply duct and air supply duct
The expansion of the air and the air delivery adjusts the angle of the air bar and header
Tight between the extension and the sealing gasket so that
Patent with a sealing flange disposed in close contact
The apparatus according to claim 1. 6. Adjustment means associated with the jack and the assembly
Claim 1 comprising a turning support means provided
The described device. 7. Patent wherein the jack is a screw jack
Claim 6 The described device. Claim 8. At least three adjustable air bars
An apparatus as claimed in claim 1 comprising: 9. At least two adjustable air bars
Are opposed so that the web passes between the two air bars
Claims located in a spaced relationship
An apparatus according to claim 1. 10. Floating the web on a predetermined path
A web dryer that dries the web while a) Upper header and web positioned above web
A lower header positioned below b) one or more adjustable air bars, each with
Has two ends and an elongate surface to release air,
The surface is in facing relationship with the web and one of the headers
One or more keys in communication with
Adjustable air bar, c) communicating with the header to supply air to the air bar;
Air supply means for d) changing the orientation of one or both headers relative to the web
By adjusting the adjustable air bath against the web
Adjusting means for changing the orientation of the extension surface of the
Dryer. 11. The orientation of the elongate surfaces is such that each surface
To rotate about an axis substantially parallel to the longitudinal centerline of the
Web drying according to claim 10, which is regulated
Machine. 12. The orientation of the elongate surfaces is such that each surface
To rotate about an axis substantially perpendicular to the longitudinal centerline of the
Web drying according to claim 10, which is regulated
Machine. Claim 13 Each with an elongate surface to release air
The apparatus further comprises a plurality of fixed air bars, and
A fixed air bar disposed on each of the elongate surfaces;
The traveling web is fixed in a substantially straight path.
And traveling as guided between the steerable air bars.
Adjustable along the length of the web Air bar spacing
Claims that are positioned in a relationship
Item 11. A web dryer according to item 10. 14. The elongate surface of the fixed air bar is
Claims oriented substantially perpendicular to the longitudinal centerline of the
A web dryer according to claim 13 15. The back pressure means comprises at least one rim;
14. The web drying device according to claim 13, comprising
Dryer. 16. The edge crest comprises an elongated crest member and a support member.
Claim 15 which is a T-shaped member having
A web dryer as described. 17. The extension weir member extends a fixed air bar.
Mounting means extending substantially vertically on the surface and
By this support member attached to the air bar
17. The method according to claim 16, which is supported at
Web dryer. 18. At least one of the fixed air bars is
Claim 13 comprising two or more rims.
Web dryer. (19) Adjustable air bar on each of the extended surfaces
Claim 1 further comprising associated back pressure means.
The web dryer according to item 0.