US3498515A

US3498515A - Fluid cushion turning rolls for supporting and guiding strip material

Info

Publication number: US3498515A
Application number: US673504A
Authority: US
Inventors: Lloyd W Johnson
Original assignee: Michigan Oven Co
Current assignee: Michigan Oven Co
Priority date: 1967-10-06
Filing date: 1967-10-06
Publication date: 1970-03-03
Anticipated expiration: 1987-03-03

Description

M rch 3, v1910 FLUID CUSHI Filed 001;. 6, 1967 SUP'PLY PLENUM SUPPLY PLENUM ON TUiiNING ROLLS FOR SUPPORTING AND .7

GUIDINGSTRIP MATERIAL 2 Sheets-Sheet 1 SUPPLY PLENUM 1 1 I 1 I 1 I 1 I I I 1 I 1 I I! //Vl/E/V70/? LLOYD 14 JOHNSON L. WQJOHNSON Mal-c1 3,

- FLUID CUSHION TURNING ROLLS FOR SUPPORTINGAND GUIDING STRIP MATERIAL 2 Sheets-Sheet 2 Filed 001;. e, 1967 I I I I I I I I! SUPPLY PLENUM m,,,,, I, I, I!

//VV/VTO/'? LLOYD W JOHNSON United States Patent 3,498,515 FLUID CUSHION TURNING ROLLS FOR SUPPORT- ING AND GUIDING STRIP MATERIAL Lloyd W. Johnson, Union Lake, Mich., assignor to Michigan Oven Company, Romulus, Mich., a corporation of Michigan Filed Oct. 6, 1967, Ser. No. 673,504 Int. Cl. B65h 17/32 US. Cl. 226-97 8 Claims ABSTRACT OF THE DISCLOSURE A fluid cushion turning roll for supporting a longitudinally moving web along a given path, through a turn subtending a substantial angle. The turning roll comprises a plurality of rows of nozzles, angularly displaced from each other around the turn with each row of nozzles extending transversely of the path at a short distance therefrom. The nozzles are preferably formed as elongated radial openings in a bar, terminating in a slot having outwardly divergent walls that open toward the path. Air, gas, or other fluid is supplied under pressure to all of the nozzles to support and guide the web; each portion of the path adjacent a row of nozzles changes direction through an angle substantially smaller than the turning angle, whereas the portions of the path intermediate the rows of nozzles are substantially linear. Fluid exhaust passages are located intermediate the nozzle rows. The open ends of the exhaust passages, adjacent the web path, are each much wider than the nozzles. The inlet to each row of nozzles comprises a restricting orifice to limit the flow of fluid through nozzles that are not actually faced by the web.

Background of the invention There are numerous applications in which a web of paper, cloth, plastic, metal, or other material is processed on a continuous basis as it is moved along a given path. In applications of this sort, it is often necessary or desirable to change the direction of the path followed by the web through relatively large turning angles, particularly in order to conserve the total space required for the processing equipment. Thus, in a treating oven or other continuous process apparatus, it may be desirable to change the direction of travel of the web through angles of 90, 180, or 270, once or several times, to avoid the necessity of construction of excessively large processing apparatus.

In many such applications, it is quite undesriable for the continuous Web to come in contact with any portion of the processing equipment. Thus, if the surface of the web is semi-fluid at any stage in the process, it might Well be damaged by contact with a conventional turning roller or any other part of the processing equipment. If the web is surfaced with material which tends to deposit on solid surfaces it contacts, the build-up of such deposits may cause irregularities which may damage the web. Materials having very soft surfaces that may =be readily scratched during processing fall within this same category. In other situations, it may be diflicult to match the speed of a turning roller to the speed of the web, especially if there is a tendency toward variation in the web velocity.

Apparatus has previously been devised for supporting and guiding a longitudinally moving web, as the web moves through a turn in its path of movement, on a substantially continuous cushion of air, gas, or other fluid. One example is an air or liquid cushion structure suggested by the British Iron and Steel Research Association and referred to as a hover bearing; this apparatus is ice described in substantial detail in Patent No. 3,097,971 to Carlisle et al. Other examples of air turning rolls are set forth in Patent No. 3,216,638 to D. I. Brickle et al. and in Patent No. 3,279,091 to F. H. Freuler.

One difliculty frequently experienced in connection with previously known fluid cushion turning roll structures results from the Bernoulli elfect produced by the flow of the fluid in a direction generally parallel to the path, from the point at which the fluid is introduced toward the point of exhaust. Thus, fluid leaving the cushion area between the turning roll apparatus and the web ordinarily passes through a relatively restricted area. The generally high velocity of fluid flow in this area produces a pressure drop which tends to pull the web into contact with the solid parts of the apparatus, defeating the primary purpose of a fluid cushion device.

Another problem that is presented with respect to known fluid-cushion turning rolls pertains to the relative width of the air cushion and the web. Of course, the fluid cushion apparatus must ordinarily be as wide as the web; otherwise, the edges of the web are likely to be uncontrolled and may be damaged. On the other hand, if the web is substantially narrower than the fluid cushion equipment, an excessive flow of fluid may be required, since it is the presence of the web that ordinarily limits the flow of fluid into the space between the apparatus and the web. Thus, known structures are usually limited to use with a web of a given width and any changes in processing requirements in this respect may render the turning roll equipment obsolete.

Summary of the invention It is a particular object of the present invention, therefore, to provide a new and improved fluid cushion turning roll for supporting and guiding a longitudinally moving web along a turning path, in which the Bernoulli effect tending to draw the Web into contact with the solid parts of the turning roll apparatus is effectively minimized or essentially eliminated.

Another object of the invention is to provide a new and improved fluid cushion turning roll which will accept a wide range of web widths without imposing excessive fluid flow requirements or requiring particular adjustment of the apparatus to accommodate web width changes.

A related object of the invention is to provide a fluid I cushion turning roll which produces relatively high pressures in areas where the web comes closer to the solid parts of the turning roll apparatus and lower pressure where the web is further away from the apparatus.

Another object of the invention is to provide a new and improved fluid cushion turning roll that is relatively simple in construction and economical of manufacture.

Accordingly, the present invention relates to a fluid cushion turning roll for supporting and guiding a longitudinally moving web along a path and through a turn subtendin-g a given turning angle, the turning roll comprising a plurality of rows of nozzles angularly disposed from each other along the turn in the web path with each row of nozzles extending transversely of the path at a short distance therefrom and with the nozzles of each row opening outwardly and preferably divergently toward the web path. The turning roll further comprises means for supplying fluid under pressure to all of the nozzles. This fluid, which may be air, gas, or other suitable fluid, impinges upon the web and supports and guides the web as it moves around the path turn, the portions of the path adjacent each nozzle row changing direction in each instance through an angle substantially smaller than the total turn angle and the portions of the path intermediate the nozzle rows being substantially linear. A series of fluid exhaust passageways are provided, one passageway intermediate each adjacent pair of rows of nozzles. Each exhaust passageway has an open end, facing the web, that is much wider in the direction of the path than the width of the adjacent nozzles, thereby precluding the normal tendency of the fluid flow from the nozzles to draw the web toward the nozzles by Bernoulli action.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and What is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention.

Brief description of the drawings FIG. 1 is a sectional elevation view of a fluid cushion turning roll constructed in accordance with one embodiment of the present invention, for turning a continuously moving web through an angle of approximately 90;

FIG. 2 is a detail view of the outlets for the nozzles in the fluid cushion turning roll of FIG. 1; and

FIG. 3 is a sectional elevation view, similar to FIG. 1, of another embodiment of the invention.

Description of the preferred embodiments FIG. 1 il ustrates a fluid cushion turning roll '10 constructed in accordance With a preferred embodiment of the present invention, some of the details of the nozzle construction employed in the turning roll being illustrated in FIG. 2. The fluid cushion turning roll is utilized to support and guide a continuous web 11 along a path that comprises a turn subtending a given turning angle. In the construction shown in FIG. 1, the path for web 11 turns through an angle of 90". Actually, the complete turn is accomplished by a sequence of three 30 turns. Two fluid cushion turning rolls using the construction illustrated in FIG. 1 can be employed conjunctively to complete a turn of 180. Continuation of the construction with an additional unit makes it possible to complete a turn of 270. With minor variations, the same construction can be employed to turn web 1 1 through virtually any desired turning angle.

Turning roll 10 includes three rows of nozzles, generally indicated by

reference numerals

21, 22 and 23. The three rows of nozzles are substantia ly identical in construction; accordingly, only row 22, which also appears in FIG. 2, is described in detail.

Thus, the row of nozzles 22 is formed by an elongated metal bar 24 in which a plurality of individual radial openings 25 are formed. Openings 25 can be formed in bar 24 by drilling the bar or, if desired, an integral casting having the openings 25 formed during the process of casting can be utilized. Openings 25 are radial openings in the sense that they are in approximate alignment with a radius of the turning angle for the path of web 11, FIG. 1.

Along the outer face of bar 24, facing the path of web- 1'1, nozzles 25 terminate in an elongated slot 2 6 that extends the length of the bar. The internal walls of slot 26 diverge outwardly toward the path of web '11. This configuration is employed to achieve divergent jets from nozzles 25 in operation of turning roll 10 as described hereinafter.

Turning roll 10 further includes means for supplying fluid under pressure to all of the nozzles of

rows

21, 22 and 23. This fluid supply means comprises a first supply plenum or duct 31 that extends the full length of row 21 of the nozzles. A similar supply duct 32 is connected to all of the nozzles 25 of row 22. A third supply plenum 33 is provided for the third row of nozzles 23. The supply ducts 31-33 are all connected to an appropriate pump,

fan, or other conventional means (not shown) for introducing fluid under pressure into the ducts and, from the ducts, into the nozzles. In most applications, the fluid iS air or some processing gas, but incompressible fluids can also be employed.

In the fluid cushion turning roll 10 there are four exhaust passages associated with the three rows of nozzles 21-23. Thus, there is an exhaust passage 40 located below nozzle row 21, in the position shown in FIG. 1. A second exhaust passage 41 is located intermediate the two rows of

nozzles

21 and 22. A third exhaust passage 42 is interposed between

nozzle rows

22 and 23 and a further exhaust passage 43 is located to the right of nozzle row 23. These exhaust passages all communicate with an exhaust duct 44 from which fluid may be exhausted by an appropriate exhaust fan, pump, or other suitable means (not shown).

In operation, web 11, which may be a plastic, cloth, metal, paper, or other material requiring drying or other processing, moves along the turning path indicated by the illustration of the web in FIG. 1. Fluid is continuously supplied under pressure to each of the rows of

nozzles

21, 22 and 23 through their

respective supply ducts

31, 32 and 33 respectively. Referring to row 22, the fluid flows outwardly of nozzles 25 and slot 26. The shape of the nozzles and the slot is such that the jets from the row of nozzles overlap at the point where the fluid impinges upon web 11, forming a continuous fluid cushion that maintains web 11 in spaced relation to the row of nozzles. The portion of the web path immediately adjacent the row 22 of nozzles changes direction through an angle A of approximately 30. At each of the

nozzle rows

21 and 23, a corresponding change is effected, so that the complete turning angle for web 11, passing around turning roll 10, is

The utilization of individual separate rows of nozzles, such as

rows

21, 22 and 23, in angular displacement from each other, in turning roll 10, effectively minimizes any tendency for web 11 to move into contact with the solid parts of turning roll 10, and particularly

nozzle rows

21, 22 and 23. The separation of the nozzle rows from each other makes it possible to reduce the velocity of the fluid, flowing away from the nozzles, as the fluid enters exhaust passages 4043. By reducing the velocity of the flow of fluid intermediate the web 11 and the solid portions of air turning roll 10, the Bernoulli elfect that would otherwise tend to pull the web toward the apparatus is maintained at a minimum. That is, the construction of fluid cushion turning roll 10 is such that the fluid is not required to escape through an elongated or otherwise extended restricted area between the web and the solid parts of the device, so that high velocity flow that might otherwise be presented is not developed. Consequently, there is no marked pressure drop immediately adjacent a solid part of the turning roll and no substantial tendency to pull web 11, by Gernoulli action, into contact with the structure of the turning roll.

The openings or nozzles 25 are quite small in relation to the size of the supply duct 32 to which they are connected. Moreover, the nozzles are of substantial length in comparison with their width. The lower end 27 of each nozzle opening 25 constitutes a restricting orifice that limits the total flow of fluid through the nozzle. If necessary, the inner ends 27 of the nozzle openings can be made smaller than the diameter of the remainder of the nozzle openings to further restrict the flow of fluid through the nozzles.

The utilization of limiting orifices in connection with the individual nozzles affords a substantial resistance to fluid flow and provides a construction in which the total resistance to fluid flow depends upon the position of web 11 with respect to each nozzle. When the web 11 extends directly across a given nozzle 25, the principal restriction upon flow of fluid outwardly of the nozzle is that afforded by the web. Under these circumstances, the pressure drop across the restricting orifice of the nozzle is quite low and the pressure against the web approaches the maximum available from the plenum chamber. On the other hand, for nozzles that are not covered by the web, as in the case of the edge nozzle 25A in FIG. 2, the web aflords no restriction on the flow of fluid from the nozzle. In this instance, the pressure drop across the restricting orifice of the nozzle increases and the total flow is limited by the orifice.

The general efl'ect of the restricting orifices for the nozzles in fluid cushion turning roll is to reduce the flow of fluid where it is not needed. This reduces the overall pump or blower requirements for the turning roll and tends to make more fluid available in areas where it is required. There is little or no significant change in operation of the turning roll for substantial variations in the width of web 11 and the turning roll can be utilized in conjunction with webs of substantially different widths without engendering excessive fluid flow requirements. Indeed, there is little necessity for adjustment of the total fluid flow despite substantial changes in web width. The highest pressures are produced in the areas where the web comes closest to the solid parts of the turning roll and the lowest pressures are developed where the web is furthest from the solid parts of the device, in the substantial linear portions of the web path extending across the wide inlets to exhaust passages 40-43.

In order to afiord a more specific illustration of the invention, in a particular application, certain design parameters relating to a typical air turning roll conforming to the construction illustrated in FIGS. 1 and 2 are set forth hereinafter. It should be understood that these data are provided solely by way of illustration and in no sense as a limitation on the invention.

Thus, in a particular installation, the nozzles for the turning roll may comprise openings of one-eighth inch diameter drilled on one-quarter inch centers in nozzle bars of thirty-six inch length, with the nozzle bars disposed to afford a turn radius of ten inches. With the illustrated construction, these orifices provide air jets that expand to a total diameter of approximately onequarter inch at a distance of one-half inch from the ends of the orifices, producing the desired overlap and continuous air cushion. The divergent walls of slot 26 and the corresponding slots in the other nozzle rows permit partial expansion within the nozzle bar so that if flow were not impeded by web 11 a band of air one-quarter inch wide would occur at a distance of one-quarter inch.

from the bar.

Plenum chambers

31, 32 and 33 are each constructed to afford a cross-sectional area of approximately nine square inches, yielding a maximum plenum chamber velocity of 4130 feet per minute at a pressure of one pound per square inch. This is approximately 20% of the nozzle velocity of 21,000 feet per minute produced through the nozzles under the given conditions. In the described construction, the walls of slot 26 diverge outwardly at an angle of approximately 7 for each wall.

FIG. 3 illustrates another embodiment of the present invention that is in many respects like that described above in connection with FIGS. 1 and 2. The fluid cushion turning roll apparatus 110 illustrated in FIG. 3 guides a moving web or strip 111 around a turn of approximately 90". As in the previous embodiment, the total turning angle of 90 is accomplished by means of three individual localized turns of approximately 30 each occurring at three rows of

nozzles

121, 122 and 123.

Nozzle rows 121-123 may be fabricated in a number of different ways. The nozzles may be formed by the drilling of individual apertures in separate solidibars that extend transversely of the path of web 11 in close spaced relation thereto, as in FIGS. 1, 2. Alternatively, the individual nozzles in each row may be formed by separate tubular elements mounted in an appropriate array and provided with a manifold or other connection means for connection to a fluid supply. In most instances the apertured bar construction described in detail in connection with FIGS. 1 and 2 is more economical.

In the construction illustrated in FIG. 3, turning roll apparatus 10 provides a different location for the limiting orifices that restrict the total flow of fluid for each of the nozzle rows. Thus, the restricting orifice for nozzle row 122 is located a substantial distance from the outlets for the nozzles and constitutes an orifice 127 leading from a supply plenum 130 to the nozzles in row 122. A similar construction is used for the restricting orifices for the other rows of

nozzles

121 and 123. All of the nozzles are fed from the one supply plenum 130.

In turning roll 110, return or exhaust passages 140-143 are again provided on each side of each row of nozzles. Moreover, the ends of the exhaust passages facing web 111 are much larger than the nozzle rows so that low velocity exhaust is assured.

The principal diflerence between turning rolls 10 and 110 is that a single supply plenum is employed in the latter construction instead of the three separate supply ducts employed in the first embodiment. Both structures provide substantial advantages in eliminating or minimizing the Bernoulli eflect tending to pull the web into contact with the solid parts of the turning roll, accomplishing this objective by the separation and spacing of their cushion nozzles. In this respect, the construction of turning roll 10 is somewhat better than that of roll 110 in that it permits the realization of lower escape velocities when wide Webs must be handled. The construction of FIG. 1, with its separate exhaust passages, imposes less restrictions on the width of the web that can be handled eflectively and, in fact, is virtually unrestricted in this regard. In both embodiments of the invention, the restricting orifices allow the equipment to handle a relatively wide range of web widths without engendering excessive fluid flow requirements for narrower webs and without requiring substantial adjustments of the turning roll apparatus. In both embodiments, it is preferred that the external walls of the nozzle rows taper away from the nozzles, as exemplified by walls 24A and 121A in FIGS. 1 and 3, respectively, so that the nozzle surfaces adjacent the webs will be quite narrow. In both, maximum pressures are produced in areas where the web comes closest to the solid parts of the turning roll and minimum pressures are developed where the web is substantially spaced from the turning roll apparatus.

What is claimed is:

1. A fluid cushion turning roll, for supporting and guiding a longitudinally moving web along a path, through a turn subtending a given turning angle, comprising:

a plurality of rows of nozzles angularly displaced from each other along the inside .of said turn in said path, each row of nozzles extending transversely of said path at a short distance therefrom and the nozzles of each row opening outwardly toward said path;

means for supplying fluid under pressure to all of said nozzles, said fluid impinging upon said web and supporting and guiding said web for movement along said path, the portions of said path adjacent each row of nozzles each changing direction through an angle substantially smaller than said turning angle and the portions of said path intermediate said rows of nozzles each being substantially linear;

and a series of fluid exhaust passageways, one passageway adjacent each side of each row of nozzles, each exhaust passageway having an open end, facing said web, that is much wider in a direction along said path than the adjacent rows of nozzles and that'includes substantialy all of the space between said adjacent rows so that there is no barrier of any substantial width parallel to said path, to preclude the tendency of high pressure fluid flowing from said nozzles to draw said web toward said nozzles by Bernoulli action.

2. A fluid cushion turning roll according to claim 1 in which each of said fluid exhaust passageways is of substantially V-shaped cross-sectional configuration with the bight of the V located inwardly of said path.

3. A fluid cushion turning roll according to claim 1 in which the internal walls of each of said nozzles are of divergent configuration opening toward said path so that the jets of fluid from said nozzles expand to overlap at said path and afford a substantially continuous cushion supporting the web in spaced relation to said nozzles.

4. A fluid cushion turning roll according to claim 1 in which the external walls of each row of nozzles are exposed to the space between the nozzles and the web, and are of divergent configuration away from said path, leading into said exhaust passageways.

5. A fluid cushion turning roll according to claim 1 and further comprising restricting orifices interposed between said supply means and each row of nozzles to limit flow through any nozzles not covered by said web.

6. A fluid cushion turning roll according to claim 5 in which said restricting orifices are located a substantial distance, inwardly of said turn, from their respective nozzle rows.

7. A fluid cushion turning roll according to claim 1 in which each row of nozzles comprises a series of spaced radial openings in a bar extending in transverse spaced relation to said path, said radial openings terminating at their outer ends in a slot that extends longitudinally of i said bar, said slot having outwardly divergent walls opening toward said path.

8. A fluid cushion turning roll, for supporting and guiding a longitudinally moving web along a path, through a turn subtending a given turning angle, comprising:

a multiplicity of nozzles angularly displaced from each other along said turn in said path, said nozzles further being distributed in a uniform pattern transversely of said path, said nozzles terminating at a short distance from said path and opening outwardly toward said path;

means for supplying fluid under pressure to all of said nozzles, said fluid impinging upon said web and supporting and guiding said web for 'movement along the turn in said path; I

each of said nozzles comprisinga restricting orifice limiting flow through the nozzle to a given maximum rate whenever the nozzle is not covered by the web;

the portions of the roll structure immediately adjacent the web path being limited to thin partition edges with no extensive surfaces along the web path.

References Cited UNITED STATES PATENTS 3,279,091 10/1966 Freuler 34156 FOREIGN PATENTS 1,134,350 8/1962 Germany.

940,229 10/ 1963 Great Britain.

M. HENSON WOOD, .TRL, Primary Examiner RICHARD A. SCHACHER, Assistant Examiner US. Cl. X.R. 34-156; 226197