US3384980A - Dryer for web or sheet-like material - Google Patents

Description

May 28, 1968 s. WALLIN DRYER FOR WEB OR SHEET-LIKE MATERIAL Filed July 12, 1965 FIG. I.

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United States Patent 3,384,980 DRYER FOR WEB 0R SHEET-LIKE MATERIAL Sven Wallin, Taby, Sweden, assignor to Aktiebolaget Svenska Flaktfabriken, Stockholm, Sweden, a corporation of Sweden Filed July 12, 1965, Ser. No. 471,113 Claims priority, application Sweden, July 13, 1964, 8,538/64 7 Claims. (Cl. 34-156) ABSTRACT OF THE DISCLOSURE A dryer for web or sheet like materials including a plurality of gas distribution boxes positioned successively in the conveying direction of the material and transversely thereto. The material being conveyed passes successively over and under the boxes making multiple passes through the dryer. At least one of the surfaces of certain of the distribution boxes contain permanent perforations for permitting gaseous medium to blow against the material at all times, at least certain of the blow boxes also containing another set or series of apertures which are shielded by flap-type valves which are arranged to shield the other apertures in order to .put them into and remove them from the drying medium circuit.

This invention relates to an arrangement in a dryer for webor sheet-like-materials, which dryer is provided with a plurality of perforated distribution boxes for the drying medium positioned one after the other in the web conveying direction and substantially perpendicular and transversely oriented with respect thereto.

Irrespective of the arrangement made in dryers in order to ensure a uniform distribution of the drying medium, for obtaining a uniform delivered product-dry or wet edges caused by a non-uniform moisture content in the material entering the dryer must be considered. This lack of uniformity may be cause-d by different 'factors, for example, it may be due to unevenness in the press rolls or dryer felts in the preceding press section. For eleminating d-ry edges formed it is known to provide the air supply devices With means adapted to reduce the medium supply to the web or to cut it off entirely in different sections transverse to the web. Owing to the reduction in drying power caused in these different sections the drying in corresponding sections of the web is retarded, so that a balancing of the moisture content is achieved. Such an arrangement can, of course, also be utilized for eliminating wet edges, in which case the medium supply is concentrated only in the Web sections in question. This arrangement, however, results in such a strong reduction in the use of the evaporation surface in the dryer that production is decreased to a substantial degree. In view of the fact that in continuous dryers of this type such a fluctuation in the production cannot be permitted, the afore-mentioned solution is not favourable in practice. Furthermore, in plants wherein the web is to be supported and conveyed by the drying medium supplied, a partial cut-off of the drying medium supply endangers the stable support and transport of the web and in certain instances may even render it entirely impossible.

This invention has as its object to solve said problem while at the same time maintaining a substantially unp CC changed capacity or production rate and a stable support and transport of the web or sheet-like material. The invention is characterized in that the perforations in one or several or possibly in all of the distribution boxes of the dryer, 'for eliminating unevennesses caused with respect to the dry content in the width direction of the material, is provided with one or several permanently open hole series and one or several holes arranged in series and provided with a plurality of individually adjustable members adapted to more or less shield necessary parts of the perforations in said adjustable series or number of series. The adjustable hole series or plurality of adjustable holes arranged in series and the nonadjustable hole series or plurality of non-adjustable holes arranged in series may be provided either in one and the same wall surface of the distribution box or in two opposite wall surfaces thereof. The first-mentioned arrangement is utilized in plants, wherein the drying medium is supplied by separate distribution boxes for the lower and upper surface respectively, the last-mentioned arrangement being utilized when the distribution boxes are mounted between two parts of the web and, thus, the drying medium can be supplied from the same distribution box to both of said parts.

A device adapted for carrying out the adjustment according to the invention comprises a plurality of adjusting members mounted in a distribution box provided with two or more hole series and a control means or device for controlling the members. The arrangement is characterized in that the adjusting member comprise a plurality of flap valves mounted within the distribution box and in close relationship with each other in the adjustable hole series, the flaps being movably connected with an angular lever, the free arm of which extends through the bottom wall of the box for supporting the flap valve and including means for connecting the lever with the aforesaid control device. For rendering possible the common adjustment of the adjusting members in a number of distribution boxes, the apparatus, accord-ing to a suitable embodiment of the invention, is constructed such that the lever extending through the bottom wall of the box includes a downwardly slotted yoke adapted to enclose and support the control device, in the present instance in the form of a coupling rod comm-on to several distribution boxes. The coupling rod at each yoke, in the illustrated embodiment, has a T-shaped cross-section projecting downwards into the slot of the yoke, which section in the one direction is defined by a sharp transition to the normal cross-section of the coupling rod to form a shoulder, which upon the movement of the coupling rod in one direction actuates the yoke in the opening direction of the lever. The portion of the cross section in the other direction is terminated by a gradual transition to the normal crosssection of the coupling rod, in such a manner, that the coupling rod upon its movement in the opposite direction is lifted from the engagement with the slot of the yoke so that the coupling rod can be turned around and released entirely. In order to safely prevent inadvertent release of the coupling rod, the rod is preferably provided on its upper surface with a bar supported by the rod and detachable from the control end of the coupling rod, the bar being of such a height that only after the removal thereof can the coupling rod be lifted out of its engagement with the yokes.

The invention will be described in a greater detail in the following with reference taken to the accompanying drawings, whereon FIG. 1 is a fragmentary vertical section through a portion of a dryer for a web, constructed in accordance with the present invention;

FIG. 2 is an enlarged fragmentary sectional view of a distribution box provided with an adjusting member according to the invention and shown in a closed position;

FIG. 3 is a fragmentary sectional view taken along the line 33 in FIG. 2; and

FIG. 4 shows the adjusting member illustrated in FIG. 2 but in an open position.

Referring now to FIG. 1, a web 1 is conveyed through the dryer in a plurality of parallel loops 1a, 1b and 1c. Underlying and transversely oriented with respect to the web, are distribution boxes 2 and 3 for the supply of drying medium to the web. As illustrated in the drawing, the boxes 2 are provided with a plurality of apertures extending transversely to and facing the web, which boxes may be considered non-adjustable for illustrative purposes. The boxes 3 are provided with a permanently open hole series extending transversely of the web, and a hole series 5 provided with a plurality of individually adjustable members 6 adapted to shield when in a first position and open when in a second position necessary portions of the perforations in said adjustable series. Control means, in the present instance in the form of a coupling rod, extends longitudinally of the web and is connected to individual members 6 of several distribution boxes. The rod 7 is adapted to be actuated by a reversing means 8, which in the embodiment shown is a compressed-air operated slide-valve motor. In FIGS. 2, 3 and 4 corresponding elements are given the same designations as above. 4a designates an alternative placing of the permanently open hole series. The adjusting members 6 include a plurality of closure means, in the present instance a plurality of flap valves 9, mounted within the distribution box and in close relationship with each other in the adjustable hole series (see FIG. 3). The fiap valves are loosely connected to an angular lever 10, the depending arm 11 of which extends through the bottom wall of the box for supporting the flap valve and connecting the lever with the aforesaid control rod 7. To prevent inadvertent leakage, a sealing washer 12 is disposed at the passage of the lever through the lower portion of the box 3. The depending arm 11 comprises a downwardly slotted yoke adapted to enclose and support the coupling rod 7. The coupling rod has at each yoke a section with a T-shaped cross-section 13 projecting downwards into the slot of the yoke. The said section is defined in one direction by a wall 14 normal to the T-shaped cross-section of the coupling rod to form a shoulder, which upon the movement of the coupling rod in the direction A (FIG. 4) actuates the yoke for movement of the flap valve to the second or open position of the lever, the said section being terminated in the other direction by a downwardly angulated or sloping wall 15. In this manner the coupling rod, upon movement in the opposite direction B (FIG. 4), can be lifted from the engagement with the slot of the yoke, thus rendering it possible to turn the coupling rod around and release it entirely to be taken out of the drying plant. By this arrangement, the flap valves can be connected and released respectively from the outside of the drying plant without requiring access to the individual valves. 16 designates a safety bar supported by the coupling rod and detachable by a screw 17 from the control end of the rod, exteriorly of the casing of the dryer. For preventing an unvoluntary release of the coupling rod, the bar is given a height that prevents the removal of the coupling rod from engagement with the yokes until the bar is removed (see FIG. 4).

Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction 7 4 and the combination and arrangement of parts may be made without departing from the spirit and the scope of the invention as hereinafter claimed.

What I claim is:

1. In a dryer for web or sheet-like materials, said dryer comprising a plurality of distribution boxes arranged successively and transversely in the conveying direction; apparatus for eliminating unevenness in the dry content transversely to the conveying direction, said apparatus including at least one permanently open hole series extending throughout the entire length of at least one of said boxes and comprising a first series of apertures, said apertures providing a passage for the drying medium to impinge upon web or sheet-like material passing through said dryer, an adjustable hole series extending throughout the length of said one distribution box and comprising a second series of apertures, said second series having a plurality of individually adjustable closure means adapted when in a first position to shield its associated aperture and when in a second position to permit passage of drying medium therethrough, and a series of control means connected to said adjustable closure means operable selectively to effect movement of said closure means from a first to a second position, whereby the drying power of the medium may be selectively varied across the entire width of the drying material.

2. Apparatus in accordance with claim 1 wherein the adjustable hole series and the non-adjustable hole series are arranged in one and the same wall surface of the distribution box.

3. Apparatus in accordance with claim 1 wherein the adjustable hole series and the non-adjustable hole series are arranged in two opposite wall surfaces of the distribution box.

4. Apparatus in accordance with claim 1 wherein said individually adjustable closure means comprises a plurality of flap valves mounted within said one distribution box and in close relation with each other, and wherein said means connectable to said adjustable closure means includes an angular lever having a free arm extending through a wall of said distribution box, and control means operable remotely from said lever and connected thereto.

5. In a dryer for web or sheet-like materials, said dryer comprising a plurality of distribution boxes arranged successively and transversely in the conveying direction; apparatus for eliminating unevenness in the dry content transversely to the conveying direction, said apparatus including at least one permanently open hole series in a plurality of said boxes and comprising a first series of apertures, said apertures providing a passage for the drying medium to impinge upon web or sheet-like material passing through said dryer, an adjustable hole series in said plurality of boxes and comprising a second series of apertures, said second series having a plurality of individually adjustable closure means comprising a plurality of flap valves adapted when in a first position to shield said second series of apertures and when in a second position to permit passage of drying medium therethrough, an angular lever having a yoke extending through a wall of said boxes and connected interiorly of said box to each of said valves, and a coupling rod to efiect movement of said closure means from a first to a second position, said coupling rod having a T-shaped cross section projecting into the slot of said yoke and supported thereby, said rod having a shoulder adjacent said T-shaped cross section whereby upon movement of the coupling rod in one direction the shoulder engages the yoke and causes said flap valves connected thereto to move into a second or open position.

6 Apparatus in accordance with claim 5 including a downwardly angulated or sloping wall on the side of said coupling rod opposite said shoulder whereby movement of said control rod in the direction opposite movement thereof towards the shoulder facilitates lifting of said coupling rod from engagement with the slot of the yoke whereby said coupling rod may be released from said yoke.

7. Apparatus in accordance with claim 6 wherein the upper surface of said coupling rod is provided with a bar supported by said rod and connected thereto, said bar having a height sufiicient to interfere with said yokes whereby only after removal of said bar may said coupling rod be lifted out of engagement with said yokes.

References Cited UNITED STATES PATENTS 3,089,252 5/1963 Daane et a1. 34-114 Justus 34-114 XR Reitzel 3454 Merrill 34-54 XR Blanchard 34159 Goldner 34-160 XR Gschwind et a1. 34115 XR Huffman 34-48 Stickle 34116 Rauskolb 34-48 FREDERICK L. MATTESON, 111., Primary Examiner.

H. B. RAMEY, Assistant Examiner.

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