Corrugated webs possess increased strength and dimensional stability compared to un-corrugated (i.e. flat) webs of the same material. For example, corrugated paperboard or cardboard is widely used in storage and shipping boxes and other packaging materials to impart strength. A typical corrugated cardboard structure known as ‘double-wall’ includes a corrugated paperboard web sandwiched between opposing un-corrugated paperboard webs referred to as ‘liners.’ The opposing liners are adhered to opposite surfaces of the corrugated web to produce a composite corrugated structure, typically by gluing each liner to the adjacent flute crests of the corrugated web. This structure is manufactured initially in planar composite boards, which can then be cut, folded, glued or otherwise formed into a desired configuration to produce a box or other form for packaging.
Corrugated webs such as paperboard are formed in a corrugating machine starting from flat webs. A conventional corrugating machine feeds the flat web through a nip between a pair of corrugating rollers rotating on axes that are perpendicular to the direction of travel of the web when viewed from above. Each of the corrugating rollers has a plurality of longitudinally-extending ribs defining alternating peaks and valleys distributed about the circumference and extending the length of the roller. The rollers are arranged so that their respective ribs interlock at the nip, with the ribs of one roller being received within the valleys of the adjacent roller. The interlocking ribs define a corrugating labyrinth through which the web travels as it traverses the nip. As the web is drawn through the corrugating labyrinth it is forced to conform to the configuration thereof, thus introducing into the web flutes or corrugations that approximate the dimensions of the pathway through the corrugating labyrinth. Accordingly, it will be appreciated that in a conventional corrugating machine flutes are introduced into the web along a direction that is transverse to the web-travel pathway; i.e. the flutes extend in a transverse (cross-machine) direction relative to the direction of travel of the web (machine direction). More simply, conventionally the flutes extend along the width of the web between its lateral edges. An example of this conventional methodology is shown in U.S. Pat. No. 8,057,621 (see
Corrugating a web in this manner can damage the paperboard or other web material because it introduces a substantial amount of oscillatory frictional and tension forces to the web leading into and while traversing the corrugating nip. Briefly, as the web is drawn between the corrugating rollers and forced to negotiate the corrugating labyrinth, the tension of the web, as well as compressive stresses normal to the plane of the entering web, oscillate in magnitude and direction as successive flutes are formed due to the reciprocating motion of the corrugating ribs relative to the web, and due to roll and draw variations in the web through the labyrinth as it is being corrugated. The oscillatory nature of the web tension through a corrugating labyrinth between corrugating rollers is well documented; see, e.g., Clyde H. Sprague, Development of a Cold Corrugating Process Final Report, The Institute of Paper Chemistry, Appleton, Wis., Section 2, p. 45, 1985. The resulting substantial cyclic peaks in web tension typically produce some structural damage in the web as it is corrugated.
In addition to undesirable tension effects, corrugating the web in the cross-machine direction introduces flutes that extend transverse to the fibers of the paperboard, which typically run the length of the web in the machine direction. Thus, flutes formed in a cross-machine direction must re-orient and introduce undulations into the paper fibers, which can also lead to reduced strength.
One way to address the aforementioned problems would be to corrugate the web in the machine direction so that the flutes extend along the direction of the web-travel pathway; i.e. in the longitudinal direction of the web itself. This is commonly referred to as ‘longitudinal corrugating’ or ‘linear corrugating.’ One issue with longitudinal corrugating is that as the longitudinally-extending flutes are formed, they necessarily consume web width (i.e. the extent of the web in the lateral, cross-machine direction) in order to convert the initially flat web into one having hills and valleys. In other words, to produce longitudinally-extending flutes the web must be gathered in the cross-machine direction such that its overall width after the flutes are formed is lower than the web width prior to forming the flutes. The ratio of the flat web's original, pre-corrugated width to its post-corrugated width is referred to as the ‘take-up ratio.’ Take-up ratios are well known for standard flute sizes in conventional transverse corrugating methods. For example, a conventional transversely-corrugated, A-fluted web exhibits a typical take-up ratio of 1.56 because the amplitude and pitch of A-flutes are such that introducing them into the web reduces the web length (i.e. its linear dimension in a direction transverse to the flutes) by 64%; i.e. making the ratio of starting length to ending length equal to 1.56. Stated another way, in conventional corrugating if one wants to end up with 100 yards of transversely-corrugated web, one has to feed 156 yards of flat web to the corrugating machine to account for the web length consumed by introducing the A-flutes.
A similar take-up ratio will be present in linear corrugating except that now that ratio will apply to the web's width in the cross-machine direction instead of to its length. This introduces a special problem because typical linear-corrugating devices such as linear-corrugating rollers cannot simultaneously gather web width and introduce corrugations without damaging and tearing the web. For example, linear corrugating rollers have circumferentially-extending ribs and valleys distributed longitudinally along the length of the rollers, wherein the circumferential ribs of one roller are received within the circumferential valleys of the opposing roller, and vice versa. Unless the web width is condensed sufficiently to account for the take-up ratio of the finished product prior to entering the nip between these rollers, it will be substantially wider than the intended product on entering the nip and would need to be instantaneously and simultaneously gathered and corrugated to produce the desired product. This cannot be achieved without damaging and tearing the web. To solve this problem, the traveling web should be gathered from its initial width to its approximate final width, based on the anticipated take-up ratio, prior to being introduced into the linear-corrugating rollers or other corrugating device.
For this reason, to date carrying out linear corrugating is impractical for commercial applications that require conventional flute sizes (e.g. A- through E-flutes) for useful web widths (e.g. final width of 50 inches). U.S. Pat. No. 7,691,045 (incorporated herein by reference) discloses a machine for gathering a traveling web laterally in the cross-machine direction prior to introducing that web to a set of rollers to introduce a three-dimensional pattern into the web. That machine utilizes a series of opposed rollers disposed along the machine direction for introducing longitudinal folds into the web beginning at the web's center. Each successive set of rollers thereafter introduces two additional folds at either side of the previously-made fold(s) until the entire web consists of a series of longitudinal folds or flutes so that the web's entire width has been gathered to a desired degree. This machine can be effective to gather the width of a paper or other web prior to downstream operations (such as corrugating or other three-dimensional forming) for relatively narrow widths that are not particularly useful on a commercial scale. Unfortunately, however, for commercial widths of, e.g. 50 inches or greater, the number of successive sets of opposed rollers that would be needed to successively form the longitudinal flutes is such that the machine would be impractically long, producing a very large footprint. Accordingly, such a machine is not capable of being retrofitted into existing corrugating lines where space is tight, and for new installations it would take up too much space to be practical.
U.S. Pat. Appl'n Pub. No. 2010/0331160 (incorporated herein by reference), which is commonly assigned with the present application, discloses another machine for gathering the width of a traveling web. That machine utilizes opposing sets of linear flute-forming bars that generally extend in the machine direction, wherein the spacing between adjacent ones of the bars generally decreases along the machine direction. The opposing sets of bars are interlaced such that the traveling web is caused to gradually conform to an intermediate longitudinally-fluted geometry as it passes between the opposing sets of bars by virtue of the decreasing lateral spacing between the bars. This machine has the advantage that it is capable of gathering the width of a traveling web in a relatively short distance of web travel, and is therefore of a practical size and footprint to be retrofitted into existing installations. However, as the paperboard web traverses the labyrinth between the opposing sets of flute-forming bars and is gathered laterally inward, individual paper elements in the web are dragged laterally across the bars thereby introducing position- and time-dependent lateral tension variations and oscillations throughout the web, which are undesirable and may contribute to damage.
It would be desirable to gather the width of a traveling web of material in the cross-machine direction according to a predetermined take-up ratio desirable for downstream processing, while minimizing or eliminating introduction of lateral tension or frictional forces in the web as a result of the gathering operation. The gathered web could then be introduced into downstream processing operations, such as longitudinal corrugating or other operations for introducing three-dimensional structure to the web, which downstream operation(s) will benefit from the lateral take-up ratio introduced in the earlier gathering operation.
A forming device is disclosed, which has an entry end and an exit end spaced apart along a machine direction. The forming device includes a plurality of flute-forming bars extending from adjacent the entry toward the exit end. At least a subset of the plurality of flute-forming bars are curved such that they converge in a cross-machine direction as they proceed toward the exit end.
A corrugating die is also disclosed, which has an entry end and an exit end spaced apart along a machine direction. The corrugating die has a continuous smooth first forming surface having a first sinus contour viewed in lateral cross-section adjacent the entry end. The first forming surface gradually evolves in the machine direction to a second sinus contour viewed in lateral cross-section adjacent the exit end. The first sinus contour has a larger amplitude and lower frequency than said second sinus contour.
A corrugating line is also disclosed, which includes the aforementioned forming device located upstream along the machine direction of the aforementioned corrugating die. The forming device is configured to deliver from its exit end a formed web of medium material that has been fluted to an intermediate longitudinally-fluted geometry. The corrugating die is configured to receive the formed web and to convert it from the intermediate longitudinally-fluted geometry to a near net shape having a lower-amplitude, higher-frequency fluted geometry that approximates a final desired corrugated geometry.
A method of forming a longitudinally-corrugated web is also disclosed. The method includes the following steps: uniformly introducing into a web of medium material a full-width array of longitudinal flutes of intermediate geometry as the web travels along a web-travel pathway in a machine direction, thereby reducing the width of the web to substantially a final width that corresponds to a take-up ratio for preselected longitudinal corrugations or other three-dimensional structure to be formed in the web at the aforementioned final width, wherein substantially no portion of the web traverses a flute-forming element in a cross-machine direction while introducing the intermediate-geometry flutes therein.
A further method of forming a longitudinally-corrugated web is also disclosed, which includes the following steps: feeding a web of medium material having an initial width in a machine direction through a longitudinal fluting labyrinth defined between opposing sets of at least partially interlaced flute-forming bars, wherein pluralities of the flute-forming bars in each set are curved such that the bars in said respective pluralities converge in a cross-machine direction as they proceed toward an exit end; and reducing the width of the web to a substantially final width by forming longitudinal flutes of intermediate geometry in the web as it passes through the labyrinth, wherein individual elements of the web passing through the labyrinth follow curved contour lines along respective individual ones of the pluralities of flute forming bars from a point where the respective element first contacts the respective bar all the way until the web exits the labyrinth.
A further forming device is disclosed, which has an entry end and an exit end spaced apart along a machine direction, and a plurality of flute-forming bars extending from adjacent the entry end toward the exit end. At least a subset of the plurality of flute-forming bars each has a variable-tangent configuration such that imaginary tangents to each of the subset of bars, at spaced locations along a length thereof, become successively nearer to parallel with the machine direction. In this manner the subset of flute-forming bars converge in a cross-machine direction as they proceed toward the exit end.
Briefly, in
Each of the aforementioned operations will now be described.
Preconditioning Apparatus
Beginning first with the preconditioning apparatus 100, preconditioning is optional and may not be necessary or desirable in every longitudinal corrugating line 1000. Accordingly, the preconditioning apparatus may be omitted. When included, the preconditioning apparatus 100 can be used to introduce or adjust a moisture content in the web 10 prior to its entering the forming device 200. Any conventional or suitable device for providing or adjusting the moisture in the web can be utilized in or as the preconditioning apparatus 100, such as spray nozzles, moisture-application rollers, etc. These will not be described further here, but exemplary moisture-conditioning devices suitable in the preconditioning apparatus are known, for example, from U.S. Pat. No. 8,057,621, incorporated above.
The preconditioning apparatus 100 may also include one or more devices to adjust the temperature of the traveling web 10 into an optimum range for downstream processing. For example, heated rollers and hot plates are conventional in the art and might be used. In some embodiments both moisture and temperature can be adjusted contemporaneously or successively via the preconditioning apparatus 100 in order to precondition the web for downstream operations. For example, it is generally desirable for the traveling web to possess between 6 and 9 weight percent moisture to protect the paper fibers. Heating the web to an elevated temperature (particularly in cold climates) but not sufficiently high to burn or otherwise damage the paper can also help relax paper fibers making them less susceptible to breakage or damage from folding and tension effects introduced in downstream corrugating operations. Both moisture- and temperature-preconditioning operations are described in the aforementioned “621 patent and elsewhere in the literature, and they will not be described further here.
Forming Device
Once the web 10 has been treated to produce the preconditioned web 10a, that web (or in the absence of preconditioning apparatus 100, the unconditioned web 10) is fed along the web-travel pathway into the forming device 200. An example embodiment of the forming device 200 is illustrated in
In a preferred embodiment, the upper frame 215 is similarly secured to the rear support posts 235 via adjustment actuators 240 as described above, so that the position or spacing of the upper frame 215 is similarly adjustable relative to the lower frame 225 at the entry end 201. Indeed, in preferred embodiments both the entry and exit ends of the upper/first frame 215, and therefore of the upper/first set of flute-forming bars 210, are independently adjustable toward and away from (e.g. height adjustable relative to) the lower/second frame 225, and therefore lower/second set of flute-forming bars 220. In an alternative embodiment, both the first and second frames 215 and 225 can be independently position-adjustable using similar actuators as described above, or adjustable relative to the opposed frame, at one or both of the entry and exit ends 201 and 202 of the forming device.
Returning to the preferred embodiment illustrated in
In the illustrated embodiment the upper array 210 has an odd number of flute-forming bars 212 (15 are illustrated) and the lower array 220 has an even number of flute-forming bars 222 (16 are illustrated). This arrangement permits the respective arrays to be interlaced with one another to define an intermediate longitudinal fluting labyrinth 250 (seen in
Returning to the figures, when an array of flute-forming bars has an odd number of such bars, e.g. bars 212 in the upper array 210 illustrated in
This can be seen in the upper array 210 illustrated in
Turning now to the lower array of flute-forming bars 220 illustrated in
Still referring to
As illustrated schematically in
It will be appreciated, again with reference to
Returning to
Turning to
In operation web-engagement portion 262 of the flute-forming bar 212,222 engages a traveling web 10 in the forming device to thereby form intermediate longitudinal flutes therein to produce the formed web 10b (see
When the flute-forming bars 212,222 are operated as zero-contact bars, preferably the engagement portion 262 of each zero-contact bar has a fluid passageway 204 therein in fluid communication with the fluid ports 205 for conducting the desired fluid (such as air) to those ports 205. The fluid exits those ports 205 to thereby provide a cushion of the fluid between the engagement portion 262 surface and the web 10 in order to support the traveling web 10 above the engagement portion 262 and thereby reduce or minimize friction as the web passes over the bars 212,222. Preferably, the fluid cushion permits frictionless support of the web as it travels through the intermediate fluting labyrinth 250 between the opposed forming bars 212,222.
Returning to
As seen in
Although the foregoing description of the supply manifold(s) 280 was given and illustrated with respect to the first frame 215 to which are mounted the first set of flute-forming bars 210, the identical arrangement can be incorporated for the second frame 225 in order to supply a cushioning fluid to the flute-forming bars 222 in the second set of said bars 220.
In one embodiment, all of the flute-forming bars 212,222 in both the upper and the lower arrays 210 and 220 can be supplied from a common fluid source and regulated from a common single metering or throttling valve located upstream of both the respective supply manifolds 280 (e.g. one manifold 280 for each set of forming bars 210 and 220). In this embodiment, a single supply manifold 280 can be used for each of the upper and lower arrays 210 and 220 (i.e. affixed to each of the respective upper and lower frames 215 and 225). Alternatively, respective pluralities of manifolds 280 can be positioned and used in connection with each set 210 and 220 of flute-forming bars, all connected in parallel to a commonly-regulated fluid source. In both these embodiments the pressures and flow rates of the supportive fluid delivered to all the bars 212,222 would be commonly controlled, resulting in substantially uniform pressures and flow rates of that fluid through the holes 205 in all the flute-forming bars 212,222.
Alternatively, the respective manifold(s) 280 associated with each set 210 or 220 of flute-forming bars 212 or 222 could be fitted with its/their own dedicated device for regulating pressure and flow rate of the fluid. Suitable regulation devices include, for example, metering or throttling valves, pressure controllers, mass-flow controllers or some combination of these. For example, a pressure regulator or mass-flow controller could be mounted in-line with the fitting(s) 285 of the respective manifold(s) 280 associated with only one set of flute-forming bars 212 or 222, between the fitting(s) and the fluid source. This embodiment would provide common control and substantially uniform pressures and flow rates for web-supporting fluid through all of the flute-forming bars 212 in the first set 210 thereof secured to the first frame 215, and separately for all the flute-forming bars 222 in the second set 220 thereof secured to the second frame 225. In other words, the flow rates and fluid pressures would be substantially uniform in each array of flute forming bars 210 and 220, but the flow rates and pressures in the first array 210 could be regulated independently of the flow rates and pressures in second array 220 and vice versa. This may be desirable, for example, for dense, heavy webs traveling in a horizontal machine direction, where additional pressure from the bottom might be useful to support the traveling web 10 centrally and against the action of gravity within the longitudinal fluting labyrinth 250. Alternatively, when the forming device 200 has a fluting labyrinth 250 that follows a curved pathway (described below) additional pressure may be desired from the side of the web 10 outside the direction the web must turn as it follows the web-travel pathway through the curved labyrinth 250.
In a further alternative embodiment, successive supply manifolds 280 distributed along the machine direction of the forming device 200 can be independently connected in fluid communication with respective and isolated longitudinal zones or segments of the flute-forming bars 212 or 222 secured to the associated frame 215 or 225. For example, one or a plurality of the flute-forming bars 212,222 can be provided in segments or having segmented distribution manifolds (e.g. segmented fluid passageways 204 and cooperating spacer passageways 203 if present), wherein each segment of the bar 212,222 or its distribution manifold correlates to a longitudinal zone of the forming device 200 extending only partway of the full longitudinal extent of that bar (including all of its segments) along the machine direction. In this embodiment, different pressures and flow rates of web-supporting fluid, or even different fluids, can be distributed to the flute-forming bars 212,222 to be emitted via fluid ports 205 at different longitudinal zones in the forming device 200. This may be desirable in order to successively increase the amount of force normal to the planar extent of the web imparted thereto by supportive fluid emitted along the lengths of the flute-forming bars 212,222. For example, the pressure (normal to the planar extent of the web) required to induce bending of that web around a radius of curvature following one of the bars 212,222 can be represented by the following relation:
As will be appreciated, the radii of curvature of the web at fixed web locations gradually decrease as longitudinal flutes are formed while the web travels in the machine direction through the labyrinth 250 between increasingly interlaced forming bars 212,222. From the foregoing relation and assuming a uniform web, as the radii of curvature decrease the amount of pressure needed to sustain that curvature will increase proportionately. Therefore, by increasing the fluid pressure emitted from fluid ports 205 at successive longitudinal zones in the machine direction, one can conserve fluid and pumping power at upstream longitudinal locations where a relatively high degree of pressure is not required to sustain the web in spaced relation to the adjacent flute-forming bars 212,222. The degree of fluid pressure and its flow rate can thus be increased at successive longitudinal zones where increased pressure may be required to sustain the web in spaced relation to the bars 212,222 at greater degrees of fluting; i.e. lower radii of curvature in the formed/forming flutes. In this embodiment, the respective supply manifolds 280 connected in fluid communication to the opposing flute-forming bars 212 and 222 in the same longitudinal zone can be supplied in parallel from the same fluid source and commonly regulated. This will ensure common fluid pressures and flow rates from both the first and second sets 210 and 220 of flute-forming bars in the same longitudinal zone.
In still a further alternative, each individual flute-forming bar 212,222 or groups of them may be provided with independent fluid-flow control, e.g. using pressure regulators or mass-flow controllers provided in-line with the distribution manifold (e.g. channel passage 203) for each flute-forming bar 212,222 but downstream of the supply manifold 280 (not shown). In this embodiment pressures and flow rates of web-supporting fluid can be individually controlled for each flute-forming bar 212,222. This could be desirable, for example, if a web-tension spike is detected downstream of the forming device 200 at only a discrete lateral (cross-machine) position in the web. In that event, the fluid pressure/flow rate of only the forming bars 212,222 at the associated cross-machine position might be increased based on a feedback control system to provide additional cushion and thus reduce friction at that location.
In each of the foregoing embodiments, a pressurized fluid such as air or steam is delivered to the supply manifolds 280 via the ports 285 using appropriate hoses, piping or tubing, which are conventional. The pressurized fluid travels through the supply passage 282, through respective supply openings 283 and into distribution manifolds associated with each of the flute-forming bars 212,222, ultimately being emitted via the associated fluid ports 205. The fluid thus provides a fluid cushion (e.g. air) above each flute-forming bar 212,222 on which the traveling web 10 can be supported or float as it traverses the intermediate longitudinal fluting labyrinth 250 in the forming device 200. The cushion provides air-greasing (i.e., lubrication) that can reduce or eliminate sliding frictional contact between the web 10 and the forming bars.
In addition to minimizing friction encountered by the web 10 as it traverses the labyrinth 250, operating the forming bars 212,222 in the zero-contact mode described here can provide an elegant mechanism of feedback control for the mean web tension via an active or passive pressure transducer (not shown) that can be used to detect the pressure in the air cushion under the web 10. Air-cushion pressure and web tension are related according to the relation P=T/R. Thus, monitoring the air cushion pressure, P, provides a real-time measure of the tension in the web. Additionally, in the zero-contact mode the cushion of air between each of the forming bars 212,222 and the traveling web 10 provides a mechanism of instantaneous damping of minute tension fluctuations in the web, because the web is free to dance above the forming bars on the cushion of air in response to transient and minute tension variances. The result is that the web is less affected by such transient tension variances. Finally, it is important to mention that “zero-contact” is not meant to imply there can never be any contact (i.e. literally “zero” contact) between the flute-forming bars 212,222 and the web 10. Even operated in the zero-contact mode as described here, some contact may occur due to transient or momentary fluctuations in mean web tension, or in localized web tension, of sufficient magnitude.
In addition or alternatively to operating in the zero-contact mode as discussed above, the web-engagement portions 262 of the forming bars 212,222 can include other features designed to minimize or eliminate friction. In one example, the surfaces of engagement portions 262 can be polished or electro polished in order reduce the frictional forces on the web as it is passing through the fluting labyrinth 250. In another example, those surfaces can be coated with a release or antifriction coating such as PTFE (Teflon®) or similarly low-friction material in order reduce the coefficient of friction at the surfaces and thus to reduce frictional forces between them and the passing web 10. In another example, those surfaces can be treated to create a hard surface coating such as by black oxide conversion coating, anodizing, flame spraying, deposition coatings, ceramic coating, chrome plating, or other similar surface treatments in order reduce the coefficient of friction.
In operation as best seen in
Thus, in case it is desired to ultimately produce a longitudinally-corrugated web having, e.g., conventional A-size flutes, the starting width of the initial flat web 10 should be 1.56 times the final desired width of the longitudinally-corrugated web to be made in the corrugating line 1000. Accordingly, if a 50-inch wide longitudinally A-fluted web is desired, then the starting flat web width should be 78 inches wide (1.56×50 inches). Similar calculations could be performed for other standard flute sizes based on the desired finished web widths. In each case, the forming device 200 can be used to reduce the width of the flat web 10 from its initial width (e.g. 78 inches for an A-fluted longitudinally-corrugated web) to the final, narrower width of the desired web (e.g. 50 inches for the A-fluted web).
The web 10/10a is fed into the forming device 200 from the rear/entry end 201 in the machine direction, so that the web passes between the opposed sets 210 and 220 of flute-forming bars 212 and 222. The position of the first frame 215 is adjusted relative to the second frame 225 at the forward/exit end 202 so that the degree of interlacement of the opposing bars 212 and 222 produces a serpentine lateral path (i.e. in the cross-machine direction, best seen in
It is also preferred that the position of the first frame 215 is adjusted at its rear or entry end 201 relative to the second frame 225. Specifically, once the degree of interlacement at the exit end 202 has been fixed, the position of the first frame 215 is adjusted at the entry end 201 (relative to the second frame 225) to select the location of a choke point 290 along the machine direction where the opposed bars 212 and 222 just begin to interlace. In operation the choke point 290 is where the entering web 10/10a first contacts or encounters the opposed first and second flute-forming bars 212 and 222 uniformly across its entire width as seen in
The location of the choke point 290 is selected based on the width of the entering web 10/10a, so that at or adjacent the choke point 290 the lateral edges of the entering web encounter and are positioned adjacent (or contact or are supported by) ones of the forming bars 212 and 222 whose lateral spacing at the exit end 202 (based on their curvature from the choke point forward) defines or approximates the desired width of the formed web 10b on exiting the forming device 200. In this manner, the lateral edges of the entering web 10/10a will follow the curvature of the respectively adjacent forming bars 212 and 222 in the machine direction as they converge laterally on approaching the exit end 202 of the forming device, and will be spaced apart by the desired width of the formed web 10b on exiting that device 200.
This will be further understood with reference to
As discussed above, the final interlacement of the opposing flute-forming bars 212 and 222 at the exit end 202 will define the take-up ratio in the forming device 200. Separately, the choke point 290 is selected based on the initial width of the entering web 290 as discussed above. In
It is noted that for a given web and take-up ratio combination, some routine iteration may be desirable to optimize the location of the choke point 290 once the take-up ratio has been fixed at the exit end 202, to account for variable degrees by which different webs might be induced to commence a fluted configuration upstream of the choke point. In such instances, the choke point location should be selected to ensure that little or no cross-machine translation of the web occurs over or relative to the flute-forming bars 212,222, at least at locations in contact with flute-forming bars. In most instances, the curvature of the bars 212,222 should prevent this even in cases when the web is induced to begin assuming a fluted configuration upstream of the choke point. But some iteration may be desirable in such cases.
It will be appreciated that in operation, as a web traverses the fluting labyrinth 250 in the machine direction, its width is gathered in the cross-machine direction through the gradual formation of a full-width array of longitudinal flutes of intermediate geometry. As the web progresses through the labyrinth 250 the array of intermediate-geometry flutes are gradually and uniformly introduced (i.e. substantially contemporaneously across the full width of the web) into the web as the degree of interlacement of opposing flute-forming bars 212,222 increases from the choke point 290 forward, and as those bars converge in the cross-machine direction based on their curvature. Based on the curvature of the flute-forming bars 212 and 222, substantially no portion of the web must traverse any of those bars in a cross-machine direction in order to converge in that direction to gather (i.e. reduce) web width. Rather, individual elements of the web follow the convergent, curved contour lines of the forming bars 212 and 222, or curved contour lines between adjacent ones of those forming bars, so that they experience only machine-direction translation relative to the forming bars 212 and 222 and no cross-machine-direction translation relative to those bars or any other flute-forming element. As a result, zero or substantially no lateral friction or tension forces, or lateral friction or tension fluctuations are introduced into the web as it traverses the fluting labyrinth 250 because the web is not stretched or pulled laterally as it passes through that labyrinth 250. In other words, in the forming device 200 no portion of the web 10 must negotiate an undulating pathway bounded by forming bars 212 and 222 in a lateral direction as it traverses one or more flute-forming bars or other flute-forming elements in that direction. When operated in a zero-contact mode as described above, machine-direction tension fluctuations can also be reduced or even eliminated because if the web does not contact the forming bars 212 and 222 there will be no friction between them. Thus, substantially every element of the traveling web moves in three dimensions (e.g., laterally, vertically and forward) simultaneously, while also maintaining substantially constant cross machine tension and machine-direction tension because the forming device 200 does not introduce lateral or longitudinal tension fluctuations in the traveling web even though it introduces longitudinal flutes therein to gather web width. Upon exiting the forming device 200 the width of the formed web 10b is adjusted to conform to or approximate the final width of a desired longitudinally-corrugated or other three-dimensional web to be made in a downstream operation, based on the lateral take-up ratio required to accommodate the final three-dimensional configuration.
The arc lengths for each of the first and second sets 210 and 220 of the forming bars 212 and 222 are selected so that the desired course adjustment of the web-travel pathway can be achieved while traversing the longitudinal fluting labyrinth 250. For example, for a 90° course correction the arc length of the sets 210 and 220 of forming bars are such that the fluting labyrinth 250 defined between them follows a course that extends π/2 radians at the desired radius of curvature. This embodiment may be desirable, for example, where it is desired to save space by feeding the initial web 10/10b from above the forming device 200 rather along a linear web path. As will be appreciated, other geometries and curvatures (e.g. twisting) of the forming-bar arrays 210 and 220 are possible and can be selected based on the geometry of a particular installation and the resultant desired web-travel pathway.
Corrugating Die
On exiting the forming device 200 the formed web 10b can be fed to a corrugating die 300 as illustrated in
Referring now to
In operation, the die halves 310 and 320 are engaged as shown in
In
Moreover, to operate the corrugating line 1000 continuously it will be necessary periodically to splice the web 10 in order to sustain a constant supply of medium material in a continuous and uninterrupted web 10. The maintenance of the aforementioned spacing between the opposing die halves will permit periodic splices in the web 10 to pass through the forming die 300 without incident, and to be formed into the near net-shaped web 10c with the rest of the continuous web. In practice, the respective die halves 310 and 320 can be mounted to frames (not shown), which will support them and maintain a relative distance between them when engaged to afford the modest degree of spacing between the opposed forming surfaces as discussed above.
To further reduce drag and the introduction of longitudinal tension fluctuations, the corrugating die halves 310 and 320 can be provided with an array of fluid ports 305 over their respective forming surfaces, through which a pressurized fluid similarly as described above can be delivered to provide a fluid cushion for supporting the web on either side. Also similarly as above, supply manifolds 380 can be distributed on each of the first and second die halves 310 and 320, connected to a fluid supply and provided in fluid communication with the fluid ports in the associated die half 310 or 320, or with respective banks of those ports in respective longitudinal zones along the machine direction. The manifolds 380 can be arranged, configured and operated analogously as described above in order to selectively supply fluid flow rates and pressures uniformly to the fluid ports in each of the first and second die halves 310 and 320, or to different longitudinal zones uniformly in the same longitudinal zone(s) in both die halves 310 and 320. In this manner, the fluid cushion can minimize or prevent frictional losses between the traveling web and the forming surfaces of the die halves 310 and 320 by reducing or even inhibiting contact between them as the web travels.
It is contemplated that corrugating dies having forming surfaces of different contours can be selected and used based on a) the particular sinus pattern of the formed web 10b to be introduced therein, and b) the final desired flute size for the finished web. Thus different corrugating dies 300 can be provided corresponding to different combinations of take-up ratio (corresponding to desired final flute size) and final web width, and can be interchanged in the corrugating line 1000 when different webs are to be made. It is contemplated, for example, that several corrugating dies 300 can be made based on standardized web sizes and flute pitches to be interchangeably installed downstream from a forming device 200 and upstream of a final corrugating apparatus 400.
Finally, it is noted that the corrugating die 300 described here is preferred in select embodiments, but it is considered optional in the corrugating line 1000. That is, while the corrugating die 300 may be desired to gradually convert the intermediate-fluted, formed web 10b to the near net-shaped web 10c that approximates a final corrugated web 10d, in embodiments it may be possible or desirable to simply feed the formed web 10b directly into a final corrugating apparatus, e.g. longitudinal corrugating rollers, to impart the final longitudinal corrugations or other three-dimensional structure therein.
Final Corrugating Apparatus
On exiting the corrugating die 300 (if present) or the forming device 200, the formed or near net-shaped web 10b or 10c can be delivered to a final corrugating apparatus 400 to yield the final corrugated web 10d having the desired longitudinal corrugations at the desired final web width. In one embodiment the final corrugating apparatus includes a pair of longitudinal corrugating rollers 410 and 420 as seen in
In operation the formed web 10b or near net-shaped web 10c is fed along the machine direction into and through the nip 450 between the corrugating rollers 410 and 420. The web 10b/10c pass through the nip 450 and is compressed between the opposing rollers 410 and 420 to form and relax the web in the sinus, longitudinally-corrugated shape so that the final corrugated web 10d will retain that shape independently from the application of any external corrugating force or when that force is removed. Whether the web entering the corrugating nip 450 is a formed web 10b directly from the forming device 200 or a near net-shaped web 10c from a corrugating die 300, its width remains substantially the same prior to, while and after traversing the corrugating nip 450. As a result, again there are preferably no or substantially no net lateral forces (cross-machine direction) on the web as it is corrugated at the corrugating nip 450.
The finished corrugated web 10d can then be fed to additional units or operations for further downstream processing. For example, the corrugated web 10d can be delivered to a conventional single-facer as known in the art, in order to apply a liner to produce a conventional single-faced web. That single-faced web can then be fed to a double-backer to apply a second liner to the remaining exposed flute crests of the web to produce conventional double-wall corrugated board, which can then be cut and shaped in a conventional manner to make packaging material, such as boxes.
Conventionally, the friction experienced by a paper web proceeding through a longitudinal corrugating machine (as disclosed in U.S. Pat. Appl'n Pub. No. 2010/0331160) was large enough to damage the paper web. This occurred because the amount of friction experienced by the travelling web, as it was gathered inward (i.e. its width reduced to accommodate the longitudinal corrugations), increased exponentially with the number of flute-forming bars against which the paper web was required to travel in the transverse, non-machine direction. Thus existing longitudinal forming devices would apply an ever-increasing amount of friction and oscillatory and transitory lateral-tension forces to the paper web that can ultimately deform and/or destroy the end product.
Conversely, the curved (e.g. parabolic) geometry of the flute-forming bars 212 and 222 of the forming device 200 described here yield a gradual forming process that uniformly and continuously forms the initial web into an intermediate sinusoidal shape having a reduced width corresponding to the desired take-up ratio, but without introducing transient or fluctuating lateral-tension forces. Because individual web elements follow a continuous curved path along curved contour lines defined by the curved flute-forming bars (see
Although particular embodiments of the invention have been described in detail, it will be understood that the invention is not limited correspondingly in scope, but includes all changes and modifications coming within the spirit and terms of the claims appended hereto.
This application is a continuation of U.S. application Ser. No. 16/600,617 filed Oct. 14, 2019, now U.S. Pat. No. 10,882,270, which is a continuation of U.S. application Ser. No. 15/969,819 filed May 3, 2018, now U.S. Pat. No. 10,479,043 which is a continuation of U.S. application Ser. No. 15/098,591 filed Apr. 14, 2016, now U.S. Pat. No. 9,981,441, which is a continuation of U.S. application Ser. No. 14/271,206 filed May 6, 2014, now U.S. Pat. No. 9,346,236, which is a continuation of U.S. application Ser. No. 14/067,783 filed Oct. 30, 2013, now U.S. Pat. No. 8,771,579 which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/721,079 filed Nov. 1, 2012, all of which are incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
654884 | Ferres et al. | Jul 1900 | A |
739276 | Allen | Sep 1903 | A |
1199508 | Swift et al. | Sep 1916 | A |
1627966 | Goodlett | May 1927 | A |
1834648 | Saunders | Dec 1931 | A |
1848583 | Swift, Jr. | Mar 1932 | A |
1981338 | Swift et al. | Nov 1934 | A |
RE20970 | Rowe et al. | Jan 1939 | E |
2163063 | Romanoff | Jun 1939 | A |
2236932 | Arentsen | Apr 1941 | A |
2257429 | Ruegenberg | Sep 1941 | A |
2398844 | Muggleton et al. | Apr 1946 | A |
2494431 | Eckstein | Jan 1950 | A |
2622558 | Mikkelsen | Dec 1952 | A |
2793676 | Hubmeier | May 1957 | A |
2960145 | Ruegenberg | Nov 1960 | A |
3002876 | Rosati | Oct 1961 | A |
3024496 | Colombo | Mar 1962 | A |
3026231 | Chavannes | Mar 1962 | A |
3046935 | Wilson | Jul 1962 | A |
3077222 | Shanley | Feb 1963 | A |
3178494 | Tisdale | Apr 1965 | A |
3245121 | Graff | Apr 1966 | A |
3300359 | Nikkel | Jan 1967 | A |
3303814 | Nitchie | Feb 1967 | A |
3306805 | Klein et al. | Feb 1967 | A |
3383234 | Nikkel | May 1968 | A |
3425888 | Kellicutt | Feb 1969 | A |
3479240 | Moser | Nov 1969 | A |
3560310 | Bolton | Feb 1971 | A |
3648913 | Ferara | Mar 1972 | A |
3676247 | Morris et al. | Jul 1972 | A |
3676263 | Tisdale et al. | Jul 1972 | A |
3692615 | Ohmori et al. | Sep 1972 | A |
3700518 | Ohmori | Oct 1972 | A |
3738905 | Thomas | Jun 1973 | A |
3773587 | Flewwelling | Nov 1973 | A |
3788515 | Middleman | Jan 1974 | A |
3892613 | McDonald et al. | Jul 1975 | A |
3966518 | Ferara et al. | Jun 1976 | A |
3981758 | Thayer et al. | Sep 1976 | A |
3993425 | Dunn et al. | Nov 1976 | A |
4086116 | Yazaki et al. | Apr 1978 | A |
4104107 | Christensen | Aug 1978 | A |
4128677 | Hoelzinger | Dec 1978 | A |
4134781 | Carstens et al. | Jan 1979 | A |
4155884 | Hughes | May 1979 | A |
4170347 | Lewis | Oct 1979 | A |
4177102 | Tokuno | Dec 1979 | A |
4179253 | Lightfoot | Dec 1979 | A |
4267008 | Owens | May 1981 | A |
4282998 | Peekna | Aug 1981 | A |
4306932 | Bradatsch et al. | Dec 1981 | A |
4316428 | Flaum et al. | Feb 1982 | A |
4316755 | Flaum et al. | Feb 1982 | A |
4338154 | Berthelot et al. | Jul 1982 | A |
4344379 | Roberts | Aug 1982 | A |
4351264 | Flaum et al. | Sep 1982 | A |
4453465 | Heller et al. | Jun 1984 | A |
4498949 | Soennichsen | Feb 1985 | A |
4544436 | Itoh et al. | Oct 1985 | A |
4569864 | McIntyre | Feb 1986 | A |
4589944 | Torti et al. | May 1986 | A |
4603654 | Mori et al. | Aug 1986 | A |
4607770 | Chodosh | Aug 1986 | A |
4757782 | Pullinen | Jul 1988 | A |
4764236 | Nikkel | Aug 1988 | A |
4806183 | Williams | Feb 1989 | A |
4841317 | Westell | Jun 1989 | A |
4863087 | Kohler | Sep 1989 | A |
4871593 | McIntyre | Oct 1989 | A |
4879949 | Vennike | Nov 1989 | A |
4886563 | Bennett et al. | Dec 1989 | A |
4935082 | Bennett et al. | Jun 1990 | A |
4991787 | Berg | Feb 1991 | A |
5016801 | Gilat et al. | May 1991 | A |
5037665 | LaMantia et al. | Aug 1991 | A |
5048453 | Eriksson | Sep 1991 | A |
5103732 | Wells et al. | Apr 1992 | A |
5185052 | Chappell et al. | Feb 1993 | A |
5203935 | May et al. | Apr 1993 | A |
5226577 | Kohler | Jul 1993 | A |
5242525 | Biagiotti | Sep 1993 | A |
5246497 | Rantanen | Sep 1993 | A |
5275657 | Duffy et al. | Jan 1994 | A |
5362346 | Bullock, Sr. | Nov 1994 | A |
5423468 | Liedtke | Jun 1995 | A |
5503547 | Funahashi et al. | Apr 1996 | A |
5508083 | Chapman, Jr. | Apr 1996 | A |
5609293 | Wu et al. | Mar 1997 | A |
5656124 | Krayenhagen et al. | Aug 1997 | A |
5660631 | Eriksson | Aug 1997 | A |
5783006 | Klockenkemper et al. | Jul 1998 | A |
5785802 | Seki et al. | Jul 1998 | A |
5792487 | Wenning et al. | Aug 1998 | A |
5947885 | Paterson | Sep 1999 | A |
6051068 | Kohl et al. | Apr 2000 | A |
6058844 | Niemiec | May 2000 | A |
6068701 | Kohler et al. | May 2000 | A |
6098687 | Ishibuchi et al. | Aug 2000 | A |
6126750 | Seiz et al. | Oct 2000 | A |
6136417 | Ishibuchi et al. | Oct 2000 | A |
6143113 | Berube | Nov 2000 | A |
6155319 | Giugliano et al. | Dec 2000 | A |
6257520 | Fujikura | Jul 2001 | B1 |
6364247 | Polkinghorne | Apr 2002 | B1 |
6378273 | Trani et al. | Apr 2002 | B1 |
6418851 | Hartmann et al. | Jul 2002 | B1 |
6470294 | Taylor | Oct 2002 | B1 |
6575399 | Lamothe | Jun 2003 | B1 |
6595465 | Lamothe | Jul 2003 | B2 |
6602546 | Kohler | Aug 2003 | B1 |
6620240 | Choi et al. | Sep 2003 | B2 |
6620455 | Mensing et al. | Sep 2003 | B2 |
6635111 | Holtmann et al. | Oct 2003 | B1 |
6692602 | Mensing et al. | Feb 2004 | B1 |
6800052 | Abe | Oct 2004 | B1 |
7115089 | Basily et al. | Oct 2006 | B2 |
7267153 | Kohler | Sep 2007 | B2 |
7595086 | Kohler | Sep 2009 | B2 |
7691045 | Basily et al. | Apr 2010 | B2 |
7717148 | Kohler | May 2010 | B2 |
7758487 | Elsayed et al. | Jul 2010 | B2 |
8057621 | Kohler | Nov 2011 | B2 |
8398802 | Kohler | Mar 2013 | B2 |
8475350 | Basily et al. | Jul 2013 | B2 |
8771579 | Kohler | Jul 2014 | B2 |
9005096 | Kling | Apr 2015 | B2 |
20020149866 | Kato et al. | Oct 2002 | A1 |
20030178524 | Newman et al. | Sep 2003 | A1 |
20030192902 | Sosalla et al. | Oct 2003 | A1 |
20040241328 | Bradatsch et al. | Dec 2004 | A1 |
20050006816 | Drut et al. | Jan 2005 | A1 |
20050194088 | Kohler | Sep 2005 | A1 |
20070138698 | Gemdt et al. | Jun 2007 | A1 |
20080317940 | Kohler | Dec 2008 | A1 |
20090325772 | Basily et al. | Dec 2009 | A1 |
20100181015 | Kohler | Jul 2010 | A1 |
20100331160 | Kohler | Dec 2010 | A1 |
20140239548 | Kohler | Aug 2014 | A1 |
Number | Date | Country |
---|---|---|
1072873 | Mar 1980 | CA |
159213 | Sep 1903 | DE |
595275 | Apr 1934 | DE |
4018426 | Dec 1991 | DE |
0037332 | Oct 1981 | EP |
1199151 | Apr 2002 | EP |
1199152 | Apr 2002 | EP |
0825017 | Jul 2002 | EP |
335445 | Jan 1904 | FR |
199538 | Jun 1923 | GB |
1544634 | Apr 1979 | GB |
2039559 | Aug 1980 | GB |
S40023188 | Aug 1965 | JP |
S42004916 | Feb 1967 | JP |
S48029595 | Apr 1973 | JP |
S48021676 | Jun 1973 | JP |
52148396 | Dec 1977 | JP |
S52156090 | Dec 1977 | JP |
S53010833 | Jan 1978 | JP |
S56160832 | Nov 1981 | JP |
H01228572 | Sep 1989 | JP |
H10034776 | Feb 1998 | JP |
2000202930 | Jul 2000 | JP |
2001063918 | Mar 2001 | JP |
2002192637 | Jul 2002 | JP |
2005193504 | Jul 2005 | JP |
2005334053 | Dec 2005 | JP |
2009209440 | Sep 2009 | JP |
2011515246 | May 2011 | JP |
1805605 | Jul 1996 | RU |
2118217 | Nov 1981 | SU |
1468766 | Mar 1989 | SU |
9947347 | Sep 1999 | WO |
200244635 | Jun 2002 | WO |
2013063551 | May 2013 | WO |
Entry |
---|
Daub, E. et al., “Gluing corrugated medium and linerboard together on the corrugator,” Tappi Journal, pp. 171-178, Jun. 1990. |
Eltex Elektrostatik GMBH, “Webmoister 70RX” Presentation. |
Inoue, M. et al., “Kinetics of gelatinization of cornstarch adhesive,” J. Applied Polymer Sci., vol. 31, pp. 2779-2789, 1986. |
Institute of Paper Chemistry, “Development of a Cold Corrugating Process,” Contract No. DE-AC02-79CS40211, Appleton, WI, Dec. 15, 1981. |
International Search Report and Written Opinion from PCT Application Serial No. PCT/US2013/067598. |
Janes, R.L., “A Study of Adhesion in the Cellulose-Starch-Cellulose System,” Institute of Paper Chemistry, Appleton, WI, Jun. 1968. |
Kroeschell, W.O., “Bonding on the corrugator,” Tappi Journal, pp. 69-74, Feb. 1990. |
Office of Industrial Technologies, Energy Efficiency and Renewable Energy, U.S. Department of Energy, “Forest Products Project Fact Sheet—Linear Corrugating,” Order #1-FP-723, Jan. 2002. |
Ononokpono, O.E. et al., “The influence of binder film thickness on the mechanical properties of binder films in tension,” J. Pharm Pharmacol, pp. 126-128, Feb. 1988. |
Page from a brochure for the Marquip Pyrobond Singlefacer. |
Printco Industries, LLC, “Chambered Reverse Angle Doctor Blade System,” retrieved from www.printco-Industries.com on Sep. 25, 2009. |
Shaw, N.W. et al., “Xitex—A revolution in board design and manufacture,” Tappi Journal 1997 Corrugated Containers Conference Proceedings. |
Sprague, C.H., “Development of a Cold Corrugating Process Final Report,” Institute of Paper Chemistry, Appleton, WI, May 1985. |
Whitsitt, W.J. et al., “High Speed Runnability and Bonding: Effects of Medium and Corrugator Conditions on Board Quality,” Institute of Paper Chemistry, Appleton, WI, May 1, 1989. |
Search Report issued in EP application No. 13 851 187.8 dated Dec. 1, 2015, 2 pages. |
European Search Report issued in European Patent Application No. 17176993.8 dated Oct. 6, 2017, 5 pages. |
Office action issued in corresponding European Patent Application No. 17176993.8 dated Jul. 5, 2018, 5 pages. |
Number | Date | Country | |
---|---|---|---|
20210078282 A1 | Mar 2021 | US |
Number | Date | Country | |
---|---|---|---|
61721079 | Nov 2012 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 16600617 | Oct 2019 | US |
Child | 17106221 | US | |
Parent | 15969819 | May 2018 | US |
Child | 16600617 | US | |
Parent | 15098591 | Apr 2016 | US |
Child | 15969819 | US | |
Parent | 14271206 | May 2014 | US |
Child | 15098591 | US | |
Parent | 14067783 | Oct 2013 | US |
Child | 14271206 | US |