US3668788A

US3668788A - Method and apparatus for drying wavily running strip with hot blasts

Info

Publication number: US3668788A
Application number: US65539A
Authority: US
Inventors: Tadashi Kobayashi
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-08-20
Filing date: 1970-08-20
Publication date: 1972-06-13
Anticipated expiration: 1989-06-13

Abstract

An arrangement for drying a strip of stock comprising the steps of running a long, thin, continuous strip of stock having a liquid coating thereon through a drying zone between overlaping convex blowing faces which cause said strip to travel along in a regular wavy running pattern by blowing film of hot air onto either side of said stock which consequently is dried while running in a practically tension-free, extensible and shrinkable state.

Description

[ 51 June 13, 1972 United States Patent Kobayashi [54] METHOD AND APPARATUS FOR 3,216,638 11/1965 Brickle et Daniels................................34/l56 X WITH HOT BLASTS Primary Examiner-Carroll B. Dority, J r. Anomey-George B. Oujevolk [72] Inventor: Tadashi Kobayshi, 1560-2 Higashihara lenma, Fuji, Japan Aug. 20, 1970 An arrangement for drying a strip of stock comprising the [22] Filed:

[2 l Appl. No.: 65,539 steps of running a long, thin, continuous strip of stock having a liquid coating thereon through a drying zone between overlaping convex blowing faces which cause said strip to travel along .34/156 [52] US. C

in a regular wavy running pattern by blowing film of hot air 7 7 l/ 6 2 2 no 5 1 m4 2 m3 "2 I 4 3 mi o C m .mF .ll. 118 55 [.1

onto either side of said stock which consequently is dried while running in a practically tension-free, extensible and shrinkable state.

2Clains,3DnwingFlgures References Cited UNITEDSTATESPATENTS PATENTEDJUM 13 I972 SHEEI 1 BF 3 FIG./

INVENTOR T mmm K013 AvAsH l QIEORGE E Q via/c LR ATTORNEY PATEHIEQJUH 1 3 I872 3, 668, 788

- sum 30F 3 Tm mm KQBM W I INVENTOR BY QKLLLRGLJL Q m L x ATTORNEY METHOD AND APPARATUS FOR DRYING WAVILY RUNNING STRIP WITH HOT BLASTS BACKGROUND OF THE INVENTION shrinkable state when the stock is coated with a chemical solution, a plastic, or another coating.

BRIEF DESCRIPTION OF THE PRIOR ART It has been a matter of great interest in industry how to dry a long, thin, continuously running strip of paper, plastic film, metal foil, orother base stock in a practically tension-free, extensible and shrinkable state when the material is coated with a chemical solution, a plastic, a pigment, an ink, or other coating. In recent years more and more new base stock and coatings have been developed, giving birth to anever-growing variety of new products. In addition, strips of such stock to be dired are becoming broader and broader. All this makes it increasingly difficult for the conventional type of drier to dry such products without unfavorably affecting their ultimate properties or to do so at higher speeds.

Specifically, the conventional drier of the belt-conveyor type must apply considerable pressure to the strip of stock in the lengthwise direction to keep it running properly, and this prevents the stock from expanding or shrinking freely, with the result that it tends to be wrinkled or curled, or lose some of its essential properties.

If the conveyor speed of the conventional drier is to be adapted to each specific type of stock to be dired so that the stock can expand or shrink freely as it is dried continuously fro'minitial evaporation of moisture to complete drying, it is necessary to use a different drive for each type of stock, plus a device for automatically efiecting fine adjustments of the tension of the stock. To allow the stock to shrink freely in width, moreover, it is necessary to minimize contact between the stock and the conveyor belt. With the conventional type of drier, these things are hard to do, and are not being done in practice.

In addition, because the conventional drier is a conveyor type, it requires a very elongated floor space for installation, and the factory space above and below the drier normally must remain empty and useless. From the viewpoint of space utilization, the conventional drier is very uneconomical. Although many attempts have been made to provide an economical drier for such stock, none, as far as I am aware has ever been successful when carried out into practice on a commercial scale.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method and apparatus for drying a long, thin, continuously running strip of paper, plastic film, metal foil, or other base stock coated with a chemical solution, plastic, pigment, or other coating without unfavorably afiecting their properties.

Another object of the present invention is to provide a method and apparatus for drying such a strip of stock as described above without mechanically marring the surface of either side thereof.

The invention also contemplates providing a method and apparatus for drying such a strip of stock as described previously without causing it to become wrinkled, curled, or otherwise physically changed.

It is also an important object of the invention to provide a more compact apparatus for drying such a strip of stock as described than those conventionally used therefore, and more particularly, to provide such an apparatus which requires less elongated floor space for installation.

SUMMARY-OF THE INVENTION Specifically, the present invention proposes to use a film of jetted hot air to keep astrip of stock to be dried running vertically in a wavy pattern while being subject to no tension inthe widthwise direction and to very little tension in the lengthwise direction, thus allowing said strip to be dried in a manner suited to its physical properties. Running in a wavy course, moreover, said strip is relieved of internal strains through flexing, and therefore finished free of curling, waving, and such other unfavorable unilateral habits. Moreover, an apparatus according to the present invention has much improved thermal efficiency and drying capacity since hot air is blown onto said running strip at a very close range.

In addition, such an apparatus can be about a third or less in size of a comparable drier of the conventional type, and does 'not require such an extremelyelongated floor space for installation as the latter does, with the result that no idle space oc- I curs above or below the apparatus. Better-utilization of plant space is thus made possible.

Other objects and advantages of the invention will become apparent from the following description of an apparatus representing a preferred embodiment thereof taken in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows jet boxes and a jet cylinder in'elevation as well as their arrangement in said apparatus;

FIG. 2 shows said apparatus in ageneral frontal elevation; and,

FIG. 3 shows schematically the inside of the apparatus of FIG. 2 in section taken on line 3-3.

DETAILED DESCRIPTION In the drawings, numeral I refers to any one of a number of jet boxes, each having a convex face 2 with jet perforations 3, which are closely distributed in the middle and less so toward the periphery.

XX represents the base line of a wave pattern, and runs roughly vertically. A number of such jet boxes as described above are arranged in a vertical row on either side of line X- X, each box having the greater part of its convex face 2 protruding across said base line and overlaping the convex face 2 of each adjacent jet box on the other side of line XX with a slight clearance between said faces. 7

The embodiment of the invention illustrated in FIGS. 2 and 3 has a drying section A1 consisting of four jet boxes arranged in two mutually confronting and staggered vertical rows as described above, a similar drying section A2 installed back to back with Al, said two drying sections thus forming group A, and a similar group B made up of drying sections B1 and B2 which are identical with A1 and A2, respectively. In addition, below and between drying sections A1 and A2, there is a jet cylinder 4 with perforations 5 on its side; and a similar jet cylinder 6 is provided below and between drying sections B1 and 82. Above and between drying sections A2 and BI, a drying roll 7 provides a means of connection between groups A and B. These groups A and B, together with a feed roll 8 which introduces a strip of stock P to be dried into group A, and a discharge roll 9 which leads the dried stock P out of group B are enclosed in a hood 10. Inside the hood 10, a hot air chamber 11 is partitioned off. Hot air supply ducts l2 and 13 lead from this chamber I l to said jet boxes I and

jet cylinders

4 and 6. j

Heaters 14a and 14b, and

exhaust ducts

15a and 15b are also provided inside said hood 10 above jet box groups A and B. Ducts l6 collect hot air from the middle between the heaters 14a and 14b and lead it to fans 17, which send said hot air to supply ducts 18. Also, said

exhaust ducts

15a and 15b lead to a fan 19, which discharges air outside, while fresh air is introduced through inlets 20.

3 OPERATION OF THE INVENTION How the present invention works is nowexplained with reference to this particular embodiment thereof. A strip of work P to be dried is introduced via the feed roll 8 into the hood 10, and runs down along the convex faces 2 of the jet boxes 1 of drying section Al, around the jet cylinder 4, up along the convex faces 2 of the jet boxes 1 of drying section A2, around the drying roll 7, down along the convex faces 2 of the jet boxes 1 of drying section Bl, around the jet cylinder 6, up along the convex faces 2 of the jet boxes 1 of drying section B2, and finally out of the hood via the discharge roll 9. Said strip P is run through this route by a take-up drive at the discharge end of said drying apparatus.

8 Air inside the'hood 10 is heated by the heaters 14a and 14b, and led via the ducts 16 to the fans 17, which sends it in hot blasts through the supply ducts 18 into the hot air chamber 1 1. From this chamber the hot air enters the jet boxes 1 and the

jet cylinders

4 and 6, from which it is blown through

perforations

3 and 5.

Since jet box groups A and B are identical in operation, the following explanation is given with reference to group A. A strip of stock P running between the partly opposing convex faces 2 of the jet boxes of each drying section is kept off each of said convex faces by hot air jetted from the perforations 3 therein. Carried on a thin film of air in this manner, said stock P follows a wavy route through said drying section. Since the stock thus running is subject to no tension at all in the widthwise direction, and can expand or shrink freely in said direction it is finished, free of wrinkling waviness. In the lengthwise direction, the stock meets with no frictional resistance from the jet boxes 1, and is kept running under only slight tension. Consequently, mechanical action hardly affects the essential properties of said stock, and when dry it shows little tendency to curling since it has been flexed repeatedly back and forth during drying.

For another thing, the surfaces of said stock P are not marred mechanically while running through said drying sections since the stock is carried on a film of hot air from each jet box.

Furthermore, since several such groups of dryingsections as described previously may be installed vertically one upon another, a drying apparatus according to the present invention may be made compact, and does not require an elongated floor space for installation as a comparable drier of the conventional type does, while being better than the latter in thermal efficiency and drying capacity.

Considering the nature of the invention, it is not limited, of course, to the particular embodiment described above, which involves two groups of jet boxes A and B.

Although the present invention has been described in conjunction with a preferred embodiment, it is to be understood that modifications and variations may be restored to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim: v

1. In an apparatus for drying a strip of stock having a wet coating thereon comprising: a rectangular frame for defining an elongated vertical path of travel for said strip of stock therein; first and second vertical rows of a plurality of boxes supported by said frame and arranged one over the other, said boxes having convex vertical faces, the boxes in one vertical row being offset with respect to the boxes in the adjoining vertical row, the convex faces in one row being nested with respect to the convex faces in said adjoining row so as to define a wavy path of travel therebetween, each face having a plurality of hot gas outlet apertures thereon; hot gas supply ducts connected to said boxes with means to supply hot gas to said ducts; and, an input and output section in said frame with stock strip feed and discharge rolls in said section to feed said stock strip nto and out of said wavy path of travel; the improvement therein wherein said first and second vertical rows of boxes form a first group, at least one second group alongside said first group, and, at least one cylinder between said first and second group at one end thereof, the circumference of said cylinder nesting between corresponding convex faces in both said first and second groups, with a plurality of hot gas apertures in said cylinder. 1

2. An apparatus as claimed in claim I, there being a plurality of parallel vertical groups with cylinders between each of said groups at the top and bottom ends thereof, so as to define an extended travel path for said stock strip.

Claims

1. In an apparatus for drying a strip of stock having a wet coating thereon comprising: a rectangular frame for defining an elongated vertical path of travel for said strip of stock therein; first and second vertical rows of a plurality of boxes supported by said frame and arranged one over the other, said boxes having convex vertical faces, the boxes in one vertical row being offSet with respect to the boxes in the adjoining vertical row, the convex faces in one row being nested with respect to the convex faces in said adjoining row so as to define a wavy path of travel therebetween, each face having a plurality of hot gas outlet apertures thereon; hot gas supply ducts connected to said boxes with means to supply hot gas to said ducts; and, an input and output section in said frame with stock strip feed and discharge rolls in said section to feed said stock strip into and out of said wavy path of travel; the improvement therein wherein said first and second vertical rows of boxes form a first group, at least one second group alongside said first group, and, at least one cylinder between said first and second group at one end thereof, the circumference of said cylinder nesting between corresponding convex faces in both said first and second groups, with a plurality of hot gas apertures in said cylinder.

2. An apparatus as claimed in claim 1, there being a plurality of parallel vertical groups with cylinders between each of said groups at the top and bottom ends thereof, so as to define an extended travel path for said stock strip.