Patent Grant
8505908
The present disclosure relates generally to a sheet deceleration apparatus and method and more specifically to a sheet deceleration apparatus and method for use in controlling the speed of a sheet of corrugated board or other sheet material as it leaves the entry or line conveyor and enters a stacking hopper.
Sheets of corrugated board, paperboard, fiberboard or other sheet material are conventionally conveyed to a stacking hopper on an entry or line conveyor. In some cases, the sheets are overlapped or shingled, while in other cases, gaps in the direction of movement are provided between adjacent sheets. Overlapping or shingling of sheets is often undesirable. For example, because shingling results in conveyance of a solid stream of sheets, sensor identification of the location of individual sheets and the presence of jams or misalignments along the conveying path can be difficult. Moreover, the shingling of sheets results in a higher sheet density along the conveyor (i.e., number of sheets per unit area of conveyor), which may result in an increase in the occurrence of jams as well as increase in the number of sheets involved in the jams. Still further, because many of the sheets have flaps or other protrusions at their leading edges, shingling of sheets can be problematic.
Typically, the sheets are projected off the end of the entry conveyor and over a stacking hopper. The stacking hopper includes a generally vertical backstop and a forwardly positioned back tamper to define a bin or area to receive the sheets in stacked form. The capacity of a particular sheet stacking apparatus is determined by the number of sheets that can be stacked per unit of time. In general, this is directly related to the speed of the entry conveyor. The greater the speed of the entry conveyor, the greater the number of sheets that can be stacked in a unit of time, and thus the greater the stacking capacity of the sheet stacking apparatus. As the speed of the entry conveyor is increased, however, the sheets are projected over the stacking hopper and against the backstop at an increased speed. At elevated speeds beyond a certain speed (usually about 300 feet per minute for certain sheets), the projection against the backstop results in the sheet bouncing back toward the entry conveyor and/or possible damage to protruding tabs or flaps on the leading edge of the sheet. Accordingly, without deceleration means, a sheet stacker has a certain maximum effective operational speed.
To improve the capacity of the stacker beyond that point, it is necessary to decelerate or slow the speed of the sheets as they leave the entry conveyor and before they reach the backstop. The prior art includes various deceleration apparatus that function to decelerate or slow the speed of the sheets in this region. One such prior art machine utilizes a set or pair of spatially fixed nip rollers at the end of the entry conveyor and prior to the stacking hopper. In this particular apparatus, the nip rollers are positioned on opposite sides of the sheet and are designed to run or be driven at the entry conveyor line speed for most of the length of the sheet. As the trailing edge of the sheet approaches these rollers, they are decelerated to a desired lower speed to slow the sheet. After the sheet has passed, the rollers are accelerated back to line speed before the next sheet arrives. A limitation of this apparatus includes the physical limitations of ramping the rollers up to about 1,000 feet per minute or more and then back down to about 500 feet per minute or less at least three times per second. A further limitation or disadvantage includes machine wear and tear associated with this repeated high speed acceleration and deceleration.
A further deceleration apparatus, such as that disclosed in U.S. Pat. No. 7,052,009, titled “Sheet Deceleration Apparatus and Method,” issued May 30, 2006, and incorporated by reference herein in its entirety, utilizes a pair of rollers moveable toward and away from one another to nip the sheet traveling between them. Specifically, this method involves delivering a sheet between the pair of rollers and moving the rollers toward one another to nip, and thus decelerate, the sheet as it enters the area of the stacking hopper.
Yet another deceleration apparatus utilizes an overhead vacuum to transport the sheet into the hopper area. This machine ramps the speed of the vacuum conveyors down to zero, kicks off the end sheet over the hopper, and then ramps back up to line speed. Although this machine is acceptable at lower speeds, it is expected that it would have drive problems at higher speeds. A combination of the deceleration apparatus of U.S. Pat. No. 7,052,009 and various embodiments of overhead vacuum means is further described in U.S. patent application Ser. No. 12/351,496, titled “Sheet Deceleration Apparatus and Method,” filed Jan. 9, 2009, which is incorporated by reference herein in its entirety.
Accordingly, there is a continuing need in the art for a sheet deceleration apparatus and method which overcomes the limitations in the art and provides a deceleration method and apparatus capable of increasing the stacking capacity of a sheet stacker. Additionally, there is a continuing need in the art for a sheet deceleration apparatus and method that can lower complexity and/or part count, increase reliability, lower power requirement, and/or allow faster conveyor line speeds.
The present disclosure is directed to a sheet deceleration apparatus and method that has particular application for use in a sheet stacking apparatus for stacking sheets of corrugated board, paperboard, fiberboard, or other sheet material from an entry or line conveyor or other delivery means. In one embodiment, the present disclosure relates to a sheet deceleration apparatus for reducing the speed of a sheet of material moving along a travel path at a first speed. The deceleration apparatus includes a rotatable cam nip being rotatable about a first axis and provided on one side of the travel path so that the sheet of material can pass by the cam nip. The cam nip includes a lobe end, such that when the lobe end is away from the travel path, the sheet of material can pass substantially unimpeded past the cam nip, and when the lobe end is near the travel path, the sheet of material is nipped by the cam nip decelerating the sheet of material from the first speed to a second speed.
In another embodiment, a method aspect of the present disclosure includes delivering a sheet of material past a cam nip, the cam nip being rotatable on a first axis and driving rotation of the cam nip, such that when a lobe end of the cam nip is away from the travel path, the sheet of material can pass substantially unimpeded past the cam nip, and when the lobe end is near the travel path, the sheet of material is nipped by the cam nip decelerating the sheet of material from the first speed to a second speed.
In yet another embodiment, the present disclosure relates to a sheet stacking apparatus having an entry conveyor, a stacking hopper, and a sheet deceleration apparatus. The entry conveyor delivers sheets of material along a travel path toward a discharge end of the entry conveyor. The stacking hopper is positioned downstream from the entry conveyor. The deceleration apparatus includes a rotatable cam nip being rotatable about a first axis and provided on one side of the travel path so that the sheet of material can pass by the cam nip. The cam nip includes a lobe end, such that when the lobe end is away from the travel path, the sheet of material can pass substantially unimpeded past the cam nip, and when the lobe end is near the travel path, the sheet of material is nipped by the cam nip decelerating the sheet of material from the first speed to a second speed.
While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the various embodiments of the present disclosure are capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present disclosure, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying Figures, in which:
a-e are schematic diagrams illustrating a method of sheet deceleration in accordance with one embodiment of the present disclosure.
a-e are schematic diagrams illustrating a method of sheet deceleration in accordance with one embodiment of the present disclosure.
The various embodiments of deceleration apparatus and methods in accordance with the present disclosure may be used with a sheet stacking machine of the type having an entry conveyor or other sheet delivery means and a stacking hopper. With specific reference to
As will be understood, the sheets 14, 15, etc. may be comprised of a pair of sheets spaced laterally from one another and being conveyed along the conveyor 10 and through the deceleration mechanism (described below) in a synchronized manner. In other embodiments, it is recognized that the sheets may be comprised of any suitable number of laterally spaced sheets, including one, two, three, four, or more sheets spaced laterally from one another. Each of the sheets 14, 15, etc. may include a leading edge 52 and a trailing edge 54. The leading edge 52 may be the front or leading edge of the sheets as they travel along the conveyor in the direction of the arrow 22, while the trailing edge 54 may be the back or trailing edge of the sheets as they travel along the conveyor 10 in the direction of the arrow 22. In
It will be understood that the stacking machine may be operable up to a certain maximum effective entry conveyor speed. If the speed of the entry conveyor 10 exceeds the maximum operational speed, the momentum of the sheets that are projected from the end of the conveyor 10 may carry the sheets against the backstop 16 with excessive force. This can cause the sheets to bounce back toward the conveyor, resulting in the machine being jammed or the sheets being misaligned or skewed in the stack 18. Projecting the sheets at excessive speeds against the backstop 16 can also result in damage to the leading edge of the sheet. This may particularly be the case if the leading edge includes, for example, flaps, tabs, or other protrusions. Accordingly, the sheet stacking machine may have a certain maximum operational entry conveyor speed (normally defined in terms of feet per minute and often about 500 feet per minute for certain sheet types) within which the stacking machine is operational for a sheet of a given size.
To improve the capacity of the sheet stacking machine by increasing the speed of the entry conveyor beyond its normal maximum speed, it may be desirable to slow down or decelerate the sheets as they are projected from the entry conveyor to an acceptable speed. This acceptable speed may be a speed that will not cause the sheets to bounce back or result in damage to the leading edges of the projected sheets. The various deceleration means, which are the subject of the present disclosure, and further details of the sheet stacking machine and system are described with reference to
In one embodiment, the entry conveyor 10 may be a belt conveyor. Although the conveyor 10 could comprise a single belt extending across the width of the apparatus, the conveyor 10 in one preferred embodiment may be comprised of a plurality of laterally spaced individual belt conveyors or belt conveyor sections. These conveyor sections may be laterally spaced from one another and include an endless belt 20. Each of the belts 20 may be supported by a plurality of belt support rollers 21. At least one of the rollers may be driven to provide the conveyor 10 with its belt or line speed. The belts 20 may move in unison to convey the sheets 14, 15, etc. along the conveyor and toward the stacking hopper 11 in the direction indicated by the arrow 22. The belts 20 may be conventional conveyor belts used in the corrugated, paperboard, or other sheet conveyance industry. Although one embodiment shows a sheet stacking machine comprising endless belts as the entry conveyor and as the means for delivering the sheets to the stacking hopper, other means currently known in the art, or which may be made available in the art, to transport or convey sheets may be used as well. Such other means do not alter the advantageous features of the deceleration apparatus and method of the present disclosure. Such other means may include rollers, overhead or underneath vacuum transport mechanisms, newspaper clamp conveying mechanisms, or any other suitable conveyance or delivery means. Such other means could also comprise top and bottom belts with the sheets sandwiched between them.
It should be noted that the entry conveyor 10, as shown in
The stacking hopper 11 may include a backstop 16, which is spaced from the forward end of the entry conveyor 10. The distance of this spacing may be adjustable to accommodate sheets of different lengths and may be at least as great as the length of the sheets (measured in the direction of travel) being stacked. The stacking hopper 11 may also include a back tamper 24 extending generally parallel to the backstop 16. As shown, the back tamper may include a generally vertical wall portion and an upper edge 25, which may be sloped toward the entry conveyor 10. This sloping edge 25 may assist in guiding the projected sheets into the stacking hopper 11 between the backstop 16 and the back tamper 24. This back tamper may be of a conventional design and include structure to square the stack 18 and to repeatedly tamp the rear edges of the sheets in the stack toward the backstop 16 to keep the stack 18 square during the stacking process. The stacking hopper 11 may also be provided with one or more side tampers and a divider if multiple side-by-side sheets are being stacked. In one embodiment, the back tamper may be spaced from the entry conveyor 10 a sufficient distance to accommodate the sheet deceleration apparatus of the present disclosure.
In one embodiment, the sheet deceleration apparatus of the present disclosure may include a first decelerator 26 and a nip or second decelerator 28. While discussed herein as typically including a first decelerator and a second decelerator, it is understood that in some embodiments, the first decelerator 26 may be eliminated, and the second decelerator 28 may provide sheet deceleration without nipping the sheets 14, 15 against a first decelerator, as is described more fully below. Where a first decelerator 26 is provided, the decelerator 26 may be positioned below or on one side of the sheet travel path, for example, on the underneath side of the sheet travel path as shown in
The decelerator 26 may include one or more skids or skid plates, rollers, or any other suitable apparatus for assisting in contacting, guiding, and/or decelerating the passing sheets 14, 15. In one embodiment, the decelerator 26 may include a plurality of laterally spaced deceleration rollers 29 positioned on one side of the projected sheet 14. In one embodiment, the rollers 29 may be mounted on a common rotation shaft 30 and spaced from one another laterally across the width of the entry conveyor 10 (see, e.g.,
The rollers 29 may also be positioned slightly rearwardly of the back tamper 24. This may permit the projected sheets to fall within the stacking hopper 11 without interference from the rollers 29. The rollers 29 may be mounted to the common shaft 30 for rotation with the shaft 30. In one embodiment, the shaft 30, and thus the rollers 29, may be driven, although some advantages of the present invention may be achieved with rollers 29 that are free spooled or that are provided with a specified rotational resistance. The rollers may be driven at a rotational speed such that the circumferential speed of the outer surface of the rollers 29 travels in the same direction as the travel direction 22 of the conveyor 10, but at a reduced speed. For example, the rotational speed of the shaft 30 and rollers 29, and thus the degree of deceleration, may be adjusted so that the circumferential speed of the rollers is about one-half to one-fourth the linear speed of the conveyor 10. The circumferential speed of the rollers may also be greater than one-half the linear speed of the conveyor 10, or it may be less than one-fourth the linear speed of the conveyor 10. The degree of deceleration can be any fraction (less than one) of the line speed of the conveyor 10. In such embodiments, the shaft 30 and thus the rollers 29 may be driven by a deceleration roller motor 90 (see
In some embodiments, the sloping wall section 25 of the back tamper 24 may be provided with a plurality of cutout portions or recesses to accommodate nesting of the rollers in those recesses. These recesses may be aligned with the rollers 29 and may permit the tamping movement of the tamper 24 without interference between the wall 25 and the rollers 29.
The position of the shaft 30 relative to the entry conveyor 10 may be spatially fixed during an operational mode. It is also contemplated, however, that means may be provided, if desired, to adjust the vertical and lateral position of the shaft 30 and thus the rollers 29 relative to the forward end of the entry conveyor 10.
The rollers 29, or alternatively skid plates, etc., can be made from a variety of materials. In one embodiment, these may include aluminum or aluminum with a urethane coating. Various plastics and other materials or combinations of materials may be used as well.
In one embodiment, the nip or second decelerator 28 may provide a rotational pinch, instead of a linear pinch. As illustrated in
As shown in
The rotation shaft 40 may be connected with and driven by a servo motor 42 or other suitable drive mechanism. The servo motor 42 may be a conventional servo motor, which is synchronized with the speed of the entry conveyor 10, the press, and/or other components of the conveyance and processing system. The synchronized servo motor may be ensure that the rotational movement of the cam nips 35 and their respective lobe ends 38 in cooperation with the rollers 29 engage or nip the projected sheet at the desired point in time (relative to the projected sheet 14) and for the desired length of time to decelerate the sheet from the line speed of the conveyor 10 to a desired lower speed. The position of the shaft 40 relative to the rollers 29 may be spatially fixed during an operational mode. It is also contemplated, however, that means may be provided, if desired, to adjust the vertical position of the shaft 40 and thus the nip decelerators 28 relative to the rollers 29. In this manner, the position of the nip decelerators 28 may be adjusted to accommodate, for example, sheets of varying thickness, increase/decrease of nip pressure, and the like.
As shown in
In an alternative embodiment, in lieu of the nip decelerator 28, any mechanism for urging the sheets downward into frictional contact with the rollers 29 may be provided without deviating from the spirit of the present disclosure. For example, a forced air generator may be positioned above the rollers 29 and configured to direct a burst of air to a portion of a sheet passing directly over the rollers 29 with a force sufficient to decelerate the sheet. As an additional example, the nip decelerator 28 may be replaced with a piston rod-type device that includes a shaft oriented perpendicularly to the conveyor having a first end for contacting the sheets and a second end coupled to a wheel that is rotatable to drive the shaft.
In some embodiments, a sheet deceleration apparatus of the present disclosure may additionally include a forced air generator configured to provide a flow of air from above and proximate the nip decelerator 28 and/or the hopper 11. The forced air generator may be in the form of a fan, blower, or the like. The forced air generator may be configured to produce a flow of air that urges the sheets downward and toward the hopper 11 as they are passed from the deceleration apparatus to the hopper 11. In this manner, increased control of the sheets may be maintained as the sheets are deposited into the hopper 11.
Having described the structural details of the deceleration apparatus in accordance with the present disclosure, the operation of that apparatus and the method aspect of the present disclosure can be understood and described as follows, with reference to
In another embodiment, illustrated in
As shown in
The rotation shaft 80 may be connected with and driven by a servo motor 42 or other suitable drive mechanism, such as described above. The servo motor 42 may be a conventional servo motor, which is synchronized with the speed of the entry conveyor 10, the press, and other components of the conveyance and processing system. The function of the synchronized servo motor may be to ensure that the rotational movement of the cam nips 65 and their respective lobe ends 68 and corresponding nip wheels 70 in cooperation with the rollers 29 engage or nip the projected sheet at the desired point in time (relative to the projected sheet 14) and for the desired length of time to decelerate the sheet from the line speed of the conveyor 10 to a desired lower speed.
Operation of the sheet deceleration apparatus of
Another system in which the various embodiments of deceleration apparatus and methods of the present invention may have particular application is illustrated schematically in
While the foregoing has been described with respect to embodiments in which adjacent sheets along a conveying path are stacked into a single hopper, it is to be appreciated that the apparatuses and methods of the present disclosure may be utilized to stack sheets in a plurality of hoppers. Such an embodiment may be advantageous in situations where sheets of varying size are being conveyed (e.g., a rotary die press forms sheets having varying dimensions).
In addition to, or as an alternative to a deceleration apparatus positioned proximate a hopper, in some embodiments, deceleration apparatuses may be positioned at other locations along a sheet conveyor and utilized to adjust, such as for purposes of calibration or synchronization, the speed of individual sheets.
In an alternative embodiment, the nip decelerators 28 of the present disclosure may be utilized in connection with the conveyance of sheets over one or more stacking hoppers 11 using an overhead vacuum conveyor. Overhead vacuum conveyors are described in U.S. Pat. No. 7,887,040, which is hereby incorporated by reference in its entirety. For example,
In addition to use for deceleration of sheets entering a stacker hopper, the deceleration apparatuses and methods of the present disclosure may be employed in conjunction with any unit operation that requires deceleration of conveyed sheets in a controlled manner. For example, the apparatuses and methods may be employed for deceleration of sheets entering and/or exiting a folder/gluer unit operation. As an additional example, the apparatuses and methods may be used in conjunction with a sheet distribution process to more accurately set the degree of separation between adjacent sheets, the overlap/shingling of adjacent sheets, etc. For example, the deceleration apparatus may be positioned immediately upstream of a takeaway conveyor and employed to set the gap distance between adjacent sheets being passed from the apparatus to the takeaway conveyor and/or set the overlap of adjacent sheets being passed from the apparatus to the takeaway conveyor.
Although the various embodiments of the present disclosure have been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the present disclosure. Accordingly, it is intended that the scope of the present disclosure be dictated by the appended claims rather than by the description of the preferred embodiment. For example, in some embodiments, the sheet stacking machine in accordance with the various embodiments of the present disclosure may be combined with an overhead vacuum means, such as but not limited to the various embodiments of overhead vacuum means described in U.S. patent application Ser. No. 12/351,496, titled “Sheet Deceleration Apparatus and Method,” filed Jan. 9, 2009, previously incorporated by reference. Such an overhead vacuum means may be used to convey the sheets over the stacking hopper.
This application claims benefit of priority to U.S. Provisional No. 61/323,728 filed on Apr. 13, 2010, the contents of which are incorporated by reference in its entirety.
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