DIRECTIONAL AIR KNIFE

An air knife includes a housing having a first end, a second end spaced from the first end in a longitudinal direction, a side wall extending from the first end to the second end, an interior, an entrance aperture configured to be connected to a source of pressurized air to increase a pressure of air inside the housing and an exit aperture. A nozzle is located at the exit aperture and has a nozzle inlet in fluid communication with the exit aperture and also has a nozzle outlet. A plurality of baffles are located in the interior of the nozzle, and each of the baffles is angled relative to the longitudinal direction. Also an assembly of a plurality of the air knives.

TECHNOLOGICAL FIELD

The present disclosure is directed to an air knife having baffles or other structure to change the direction of air exiting the air knife.

BACKGROUND

Air knives are known that comprise a tube having a slit-like opening. Pressurized air is fed into the tube from a blower or source of compressed air so that the air exits the opening in a sheet at high speed. Such air knives are commonly used to clean and/or dry materials moving past the air knife on a conveyor. U.S. Pat. No. 6,742,285, which is incorporated herein by reference, shows a general example of an air knife.

Air knives are currently used above conveyors to dislodge scrap from sheets of material, such as paperboard, carried by the conveyors. These air knives are mounted across the conveyor so that they extend perpendicular to the direction of sheet movement along the conveyor. Air knives mounted in this manner tend to blow scrap toward the entrance to the conveyor, but due to the small spacing between the sheets on the conveyor, they do not always blow the scrap off the sheets. Instead, scrap may be blown backward onto upstream sheets. Mounting an air knife at an angle to the sheet travel direction as shown in U.S. Pat. No. 6,742,285 for example, might be useful in some circumstances; however, in many conveyors there is no room to mount an air knife as taught in this reference.

SUMMARY

The air knife of the present disclosure is intended to be used in a conveyor for moving sheets of corrugated paperboard from a die cut machine to a stacker. The air knife is configured to blow scrap at an angle to the sheet travel direction while the air knife itself is mounted substantially perpendicular to the sheet travel direction. This is accomplished by providing air guides or baffles in or at the opening of the air knife to direct air exiting the air knife at an angle to the sheet travel direction. Optionally, the baffles may be movable to change the angle of the exiting air.

A first aspect of the disclosure is an air knife comprising a tubular housing having a first end, a second end spaced from the first end in a longitudinal direction, a side wall extending from the first end to the second end, an interior, and an aperture configured to be connected to a source of pressurized air to increase a pressure of air inside the tubular housing. There is at least one opening in the side wall of the housing, and a nozzle is located at the at least one opening. The nozzle has a nozzle inlet in fluid communication with the at least one opening, a nozzle outlet spaced from the nozzle inlet, and a nozzle interior. A plurality of baffles are located in the nozzle interior, each of the baffles having a first end at the nozzle inlet and a second end at the nozzle outlet. The tubular housing is divided into a first half and a second half by an imaginary plane perpendicular to the longitudinal direction, and the second end of each of the baffles is longitudinally offset from the first end of each of the baffles.

Another aspect of the disclosure is an air knife comprising a tubular housing having a first end, a second end spaced from the first end in a longitudinal direction, a side wall extending from the first end to the second end, an interior, and an aperture configured to be connected to a source of pressurized air to increase a pressure of air inside the tubular housing. There is at least one opening in the side wall of the housing, and a nozzle is located at the at least one opening. The nozzle has a nozzle inlet in fluid communication with the at least one opening, a nozzle outlet spaced from the nozzle inlet, and a nozzle interior. A plurality of baffles are located in the nozzle interior, each of the baffles having a first end at the nozzle inlet and a second end at the nozzle outlet. The tubular housing is divided into a first half and a second half by an imaginary plane perpendicular to the longitudinal direction, and the baffles are configured such that when the pressure of the air inside the tubular housing is greater than a pressure of air outside the tubular housing air exits the nozzle outlet at an acute angle relative to the plane.

Yet another aspect of the disclosure comprises an air knife with at least one housing having a first end, a second end spaced from the first end in a longitudinal direction, a side wall extending from the first end to the second end, an interior, an entrance aperture configured to be connected to a source of pressurized air to increase a pressure of air inside the housing and an exit aperture. A nozzle is mounted or formed at the exit aperture, and the nozzle has a nozzle inlet in fluid communication with the exit aperture, a nozzle outlet spaced from the nozzle inlet, and a nozzle interior. A plurality of baffles are located in in the nozzle interior, and each of the baffles has a first end at the nozzle inlet and a second end at the nozzle outlet. Each of the baffles is angled relative to the longitudinal direction.

A further aspect of the disclosure comprises an air knife assembly having a conduit having at least one wall and a plurality of openings in the at least one wall and at least one air knife connected to the conduit. The air knife assembly comprises a first air knife having a first housing having an entrance aperture connected to a first one of the plurality of openings and having an exit aperture, and a first nozzle having an interior, an inlet in fluid communication with the exit aperture of the first housing, and a plurality of first baffles in the interior of the first nozzle and angled in a first direction, and a second air knife having a second housing having an entrance aperture connected to a second one of the plurality of openings and having an exit aperture, and a second nozzle having an interior, an inlet in fluid communication with the exit aperture of the second housing, and a plurality of second baffles in the interior of the second nozzle angled in a second direction.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for purposes of illustrating presently preferred embodiments of the present invention and not for the purpose of limiting same, and whereinFIGS.2-44are drawn to scale,FIG.1shows a conveyor10supporting a sheet of material12, such as corrugated paperboard, as it passes beneath an air knife14. The conveyor10moves in a downstream or sheet-transport direction, and the air knife14is mounted perpendicular to the sheet transport direction. That is, the length direction or longitudinal direction of the air knife is perpendicular to the downstream direction.

The air knife14includes a tubular housing16connected to a blower17or other source of pressurized air by a single connector15attached to an aperture18in the tubular housing16as illustrated inFIG.1. In the alternative (not illustrated), the source of pressurized air may be connected to both ends of the tubular housing. As used herein, “source of pressurized air” can mean a fan or blower17for driving air into the tubular housing16to increase the air pressure inside the tubular housing or a cylinder of compressed air (not illustrated) connected to the tubular housing to increases the pressure in the tubular housing16. The tubular housing16is divided into two halves by an imaginary plane19perpendicular to the longitudinal direction of the tubular housing.

As shown inFIG.2, the housing16includes an elongated nozzle20having a nozzle inlet21in fluid communication with the interior of the housing16and a slit-shaped nozzle outlet22through which pressurized air passes before impacting against the sheet of material12on the conveyor10. In this embodiment, the nozzle20and the housing16are formed as one piece. The relatively narrow width of the nozzle outlet22, which is narrower than the width of the nozzle inlet21, increases the speed of the air exiting the air knife10to form a sheet of air that impacts against the sheet of material12and dislodges scrap resting on the sheet of material12. A second air knife (not illustrated) may also be provided below the conveyor10to blow air on the conveyor bottom (assuming the conveyor is formed from multiple parallel belts or has gaps or openings) to dislodge scrap attached to the bottoms of the sheets of material12. The second air knife may be identical to the first air knife and will not be further described.

For the air knife of the present disclosure, the speed and volume of air emitted from the nozzle20should be sufficiently high that loose and partially attached chads (scrap material partially attached to the sheets of material on the conveyor10) can be moved to the sides of the conveyor without damaging the sheets of material themselves.

The housing16and the nozzle20preferably extend perpendicular to the shect transport direction, and the nozzle20may be tilted (that is, the housing16may be rotated around its longitudinal axis) so that the nozzle20faces upstream at an angle of, for example, 30 degrees while the longitudinal direction of the nozzle20remains perpendicular to the sheet transport direction. It is sometimes desirable to direct the nozzle20at an angle to the sheet transport direction (so that the housing16is not perpendicular to the sheet transport direction) to impart transverse movement to scrap on the sheets of material12to better move the scrap toward and/off the edges of the sheets of material12. This can be done by mounting the entire housing16at an angle to the sheet transport direction; however, many conveyors do not have sufficient space to allow for an angled mounting. Embodiments of the present disclosure address this problem by providing baffles or vanes to direct the air exiting the housing16at an angle to the sheet transport direction while the housing of the air knife remains perpendicular to the sheet transport direction.

In a first embodiment, at least one baffle assembly24, which includes a plurality of individual baffles26, is provided in the interior of the nozzle20with a first end of each baffle located near the nozzle inlet21and a second end of each baffle near the nozzle outlet22. The baffles26may be located entirely inside the nozzle20; in the alternative, the first ends of the baffles may extend into the interior of the tubular housing16and/or the second ends of the baffles may project out of the nozzle outlet22. The sectional view ofFIG.2shows one of the baffles26, andFIGS.3and4show the baffles26supported by a common baffle support member28.

Each of the baffles26includes a main portion30and a tapered distal portion32which is shaped to conform to the interior of the nozzle20and span a portion of the interior so that air from the housing16exits the air knife10between adjacent pairs of the baffles26. The baffle support member28includes a profiled bead27configured to be received in a channel29in the interior of the housing16to secure the baffle assembly24in a desired position and orientation relative to the nozzle outlet22. If the baffles26were not present, air exiting the nozzle20would flow perpendicular to the longitudinal axis of the housing16(the original air exit direction). The baffles26are shaped such that the second end of each baffle is longitudinally offset from the first end of each baffle and thus angled such that air exiting the air knife14flows toward one side (if all baffles are angled in the same direction) or both sides (if two sets of the baffles26are angled in opposite direction) of the air knife10and thus toward one or both sides of a centerline of the conveyor10. In some cases, the baffles26can be curved instead of flat as illustrated. When flat baffles26are discussed, the baffles may be described as being “angled” relative to an original airflow direction perpendicular to the longitudinal center line of the tubular housing16; this disclosure applies to curved baffles as well.

The baffle assembly24is preferably formed from plastic, but can also be formed from metal or other materials. In particular when formed from plastic, the baffle assembly24can be 3D printed or formed by another additive manufacturing process. In addition, conventional molding methods can be used.

The number and spacing of the baffles26can vary as can the angle of the baffles26relative to the original air exit direction.FIG.4shows the baffles26making a 30 degree angle relative to the original air exit direction; however, the baffles26may be directed at angles of about 30 to 60 degrees relative to the original exit direction. The angle selected may be based on the amount of air flow through the nozzle20and/or the amount and/or type of scrap that needs to be dislodged from the sheets of material12. Larger or smaller numbers of baffles may also be used.

Referring again toFIG.1, the baffles26can be arranged such that they are all angled toward one side of the conveyor10-to the right inFIG.1, for example. However, preferably, a first set34of the baffles26is angled away from the center plane19of the air knife14toward the left side of the conveyor10, and a second set36of the baffles26is angled away from the center plane19of the air knife14toward the right side of the conveyor10. With this configuration, scrap on the upper surface of the sheet of material12only needs to be moved at most across half the width of the sheet of material12before falling off a side edge. The baffles26each include a curved portion29where they connect to the baffle support member28to help guide air into the spaces between the baffles26. The length of the curved portion29can be made longer or, optionally, the baffle26itself can be curved along some or all of its length.

FIGS.6-9show a second embodiment of a baffle assembly38mounted in the tubular housing16which includes a plurality of individual baffles40attached to a common baffle support member42with a curved air guide wall41provided at the connection of each of the baffles40and the baffle support member42. The baffles40are angled at 60 degrees relative to the original exit direction of air from the nozzle20and are more closely spaced (e.g., by about 1 inch) than the baffles26of the baffle assembly24of the first embodiment (which are spaced by about 2 inches). Each of the baffles40includes a main portion44and a tapered distal portion46which are shaped to conform to and span the interior of the nozzle20. The baffle support member42includes a profiled bead48that is receivable in the channel29inside the housing16to hold the baffle assembly38in position.

FIGS.10-13show a third embodiment of a baffle assembly50mounted in the tubular housing16which assembly includes a plurality of individual baffles52attached to a baffle support member54with a curved air guide wall51at the connection of each baffle52to the support member54. The baffles52are angled at about60degrees to the original exit direction of air from the nozzle20and are more closely spaced (by about 0.69 inches) than the baffles26and40of the first and second embodiments. Each of the baffles52has a main body portion56and a tapered distal portion58, and the baffles52are shaped to conform to and span the interior of the nozzle20. Furthermore, in this embodiment, the tips60of the distal portions58of the baffles52project through the nozzle outlet22as shown inFIG.10, which may sometimes provide improved directional control of the air flow. The baffle support member54also includes a profiled bead62that is receivable in the channel29in the housing16to hold the baffle assembly50in place.

FIGS.14-17show a fourth embodiment of a baffle assembly70that includes a plurality of individual baffles72attached to a baffle support member74and mounted in the tubular housing16at a space of about 0.3 inches. The baffles72are angled at about 60 degrees to the original air exit direction from the nozzle20. Each of the baffles72has a main body portion76and a tapered distal portion78shaped to span the width of the nozzle20. Each of the baffles72also includes a center rib80on one side thereof which rib80includes a tapering upper portion82and a thin lower portion84having a substantially constant width. The rib80may help to improve the uniformity of air flow exiting the slit22. The baffle support member74also includes a profiled bead86that is received in the channel29of the housing16to hold the baffle assembly70in place.

FIGS.18-33show a second embodiment of an air knife100according to the present disclosure. In this embodiment, as can be seen inFIGS.20and21, for example, baffles are formed in a nozzle structure that is attached to a tubular housing rather than being located in a nozzle20that is formed integrally with a housing16as shown in the first embodiment. Referring now to the air knife100ofFIG.18, (shown in perspective view inFIG.23and exploded inFIG.24), the air knife100includes a tubular housing102having longitudinally spaced ends104either or both of which includes an aperture103that is connectable to a blower or other source of pressurized air (not illustrated). The housing102includes a plurality of holes105(FIG.21) or slots106(FIG.24) in its cylindrical side wall108, but a single slot106or a greater or lesser number of holes105and/or slots106could be provided. The slots106allow pressurized air to exit the housing102.

A nozzle110is connected to the housing102such that the slots106of the housing are in fluid communication with an interior112of the nozzle110. The nozzle110may be attached to the housing102by a plurality of screws114as illustrated in the drawings or by welding or the use of an adhesive or other suitable fastening method. Baffles116inside the nozzle110direct air exiting the nozzle110at an angle to the sheet transport direction. That is, if the baffles116were not present, air would exit through the nozzle outlet118at the end of the nozzle110in a direction perpendicular to the longitudinal direction of the housing102; the baffles116direct the exiting air at an angle to that perpendicular direction. The baffles116are preferably molded from the same material used to form the nozzle110; in the alternative, they can be attached to or formed on the surface of the nozzle after the nozzle110is produced.

Referring now toFIG.21, which shows a detail of the portion of the nozzle110located in the center of the housing102, a first set120of the baffles116are angled to the left of the center plane119in the figure while a second set122of the baffles110are angled to the right of the center plane119.FIG.22, a detail view of the right end of the nozzle110ofFIG.17, show baffles116of the second set122of baffles. The nozzle110thus emits streams of air in opposite directions, away from the center plane119of the air knife100to blow scrap toward the opposite sides of sheets of material12on a conveyor beneath the air knife100. The baffles116could alternately be angled to direct exiting air toward the center plane119of the of the air knife100, for example, if two sheets are being carried along the conveyor with a gap in between the sheets or if another reason exists to move scrap toward the center of the conveyor10.

FIGS.26-32show different configurations of the baffles116inside embodiments of the nozzle110. The baffles116and the interior112of the nozzle112can also be seen inFIG.32.

FIG.33shows an alternate arrangement of baffles130inside a nozzle132. As can be seen inFIG.33, the angle between the baffles130and the center plane119increase from the center to the each edge of the nozzle132(FIG.33only shows one half of the nozzle132). InFIG.33, the angle of each baffle130is different than the angle of an adjacent baffle so that the baffle angle changes from about 0 degrees at the center of the nozzle130(that is, air in the center of the baffle is directed straight down in the original air exit direction) and air at the extreme right end of the nozzle132is angled at about 55 degrees.

The angle of each baffle can be different, as shown, or several baffles may be angled at the same angle. For example, although not illustrated, a first subset of, e.g., five baffles can be angled at 10 degrees, a next subset of five baffles can be angled at 20 degrees, etc. from the center plane119. Finally, in some instances, it may be desirable to decrease the angle of the baffles from the center of the nozzle132to each end of the nozzle132so that, for example, the baffles near the center of the nozzle132make an angle of 60 degrees to the original air exit direction and the angle of the baffles at the edges of the nozzle132is, e.g., 30 degrees.

FIG.34shows a nozzle according to a further embodiment of the disclosure in which the baffles140in a nozzle142are adjustable from0degrees to a maximum angle of, for example, 60 degrees either toward or away from a center plane or an end of a housing. This is accomplished by providing the baffles140, one of which is shown by itself inFIG.35, with a bottom opening144by which a lower end of the baffle140is pivotably mounted to a pin146in the interior of the nozzle142while a second end of the baffle140includes a slot148in which a pin150of an actuator in the form of a slider152is received. Moving the slider152back and forth, either manually or by an actuator (not illustrated) changes the angle between the baffles142and the exit154of the nozzle142. This may be useful, for example, when it is sometimes desirable to allow air to exit the nozzle142in the original air exit direction (with the baffles perpendicular to the nozzle exit154) and sometimes desirable to direct the air from the nozzle142at a positive or negative angle.

Additional embodiments of air knives and air knife assemblies are shown inFIGS.36-44.FIG.36shows a conveyor200having an upper deck202that includes a plurality of belt support assemblies204each supporting an individual belt206and also shows a lower deck208with a plurality of support wheels210. The lower runs212of the belts206and the tops of the support wheels210define a sheet transport path214or boardline along which sheets of material travel through the conveyor200in a sheet transport direction, which is a right-to-left direction inFIG.36. The tops of the support wheels210are tangent to a plane. The lower runs212of the belts206in many cases are located above the plane, but in some cases, when the support wheels210are laterally offset from the belts206, the lower runs of the belts206may be located at or beneath the plane so that sheets of material moving through the conveyor200are slightly flexed which, in some applications, provides for better control of the sheets.

The belt support assemblies204are mounted adjacent to each other in a transverse direction perpendicular to the sheet transport direction to form rows, and the upper deck202may include two or more rows of the belt assemblies204arranged in the sheet transport direction. First and second belt support assemblies204spaced apart in the sheet transport direction can be seen inFIG.36, and a plurality of transversely spaced belt assemblies can be seen inFIG.44. A first air-knife assembly216and a second air knife assembly218are also shown inFIG.36.

FIGS.37and38show the air knife assembly218removed from the conveyor200for illustration purposes. The assembly218includes first and second ducts220for delivering pressurized air to a conduit222via duct outlets224. In the present disclosure, the conduit222has a square or rectangular cross section, but conduits having different cross sections can be used if desirable based on the environment in which the air knife assembly is used. As can be seen inFIG.38, the conduit222has a side wall226and an interior228and a plurality of conduit outlets230in the side wall226. A plurality of housings232each have at least one side wall234that defines an interior236, an entrance aperture238connected to one of the conduit outlets230and an exit aperture240.

A nozzle242is connected to each of the exit apertures240of the housings232for increasing the speed of air exiting the nozzle242. Each of the nozzles242has an entrance end244inserted into or otherwise connected to the exit aperture240of a housing, and a tapered exit end246(see, e.g.,FIG.40) having a slot-like opening248so that air exiting the opening248forms a high velocity sheet of air. A plurality of baffles250are located at the exit end246and angled to direct air exiting the opening248at a desired angle relative to a longitudinal centerline of the housing232.

The ducts220, conduit222, housings232, and nozzles242are shown as being formed of sheet metal connected together in a substantially air-tight manner so that air from the ducts220is guided to the openings248with minimal loss. However, one or more of the ducts220, conduits222, housings232, and nozzles242could be extruded from plastic or metal or formed from any other materials or combinations of materials suitable for carrying and guiding pressurized air (or other gas).

With reference toFIG.38, the baffles250are angled at a 45° angle relative to an imaginary center plane252that divides the conduit222into two halves so that all baffles to one side of the center plane252are angled in one direction (e.g., to the left) and all baffles to the other side of the center plane252are angled in the opposite direction (e.g., to the right). The disclosure, however, is not limited to the use of baffles at a 45° angle, and other angles and/or combination of baffle angles could be used when appropriate. The baffles of the nozzle242C located in the center of the air knife assembly218are also angled to the left and right of the center plane252which passes through the nozzle242C so that this center nozzle242C directs air in two opposite directions.

When mounted to the upper deck202of the conveyor200, the air emitted from all nozzles242at the angles shown tends to blow scrap or other debris on sheets of material in the sheet transport path214away from the longitudinal center line of the sheet transport path214. This angled air flow makes it more likely that the scrap will be moved off the tops of sheets of material in the sheet transport path so that it can fall between the support wheels210rather than remain trapped between the belts206and the support wheels and/or between the belts206and sheets of material moving through the conveyor200.

The air knife assembly218allows the nozzles to be located and specific air flows to be achieved in desired positions adjacent to the belts206without the need to insert a conduit through the interiors of the closed loops formed by each of the belts206. The disclosed configuration thus allows for the use of an air knife assembly in conveyors in which the use of a conventional air knife would be impossible or impracticable.FIG.41shows that an air knife assembly216can be located between two belt support assemblies204that are spaced apart in the sheet transport direction and or that an air knife assembly218can be located between two belt support assemblies204that are spaced apart in the transverse direction, partially hiding the air knife assembly218in the view ofFIG.41. The locations of two air knife assemblies216,218relative to two belt support assemblies can also be seen inFIG.36.

A second embodiment of an air knife assembly260is illustrated inFIGS.42-44. In this embodiment, elements common to the first embodiment are identified by like reference numerals. The air knife assembly260differs from the air knife assembly218in that the nozzles262of the air knife assembly260are wider in the transverse direction so that each end of the nozzle can extend into the closed loop formed by each of the belts206as shown inFIG.44. In this manner, the air emitted from the nozzles262can be directed not only against the tops of the sheets of material moving along the sheet transport path214but also against the insides of the closed loops formed by the belts206. Angled baffles250inside the nozzles262can be seen inFIG.43.

Scrap in a conveyor, when dislodged from the surface of the sheets of material in the sheet transport path214may not fall directly downward and out the conveyor. Instead, turbulent air inside the conveyor may lift the scrap above the sheet transport path and cause the scrap to become trapped between the belts206and the guide wheels264that support them. This can lead to jams or even cause the belts206to come off the guide wheels264. Extending portions of the nozzles262directly over the belts206inside the closed loop formed by each of the belts may better dislodge scrap than the nozzles242of the air knife assembly218which are slightly transversely offset from the belts.

The present invention has been described herein in terms of presently preferred embodiments. Additions and modifications to these embodiments will become apparent to persons of ordinary skill in the art upon a reading of the foregoing disclosure. It is intended that all such modifications and additions for a part of the present invention to the extent they fall within the scope of the several claims appended hereto.