Corrugated paperboard box converting machine retrofit for eliminating edge crush test degradation

A box machine is retrofitted by removing the upper feed roll, sheet feeder, and by replacing the lower feed roll with a drive shaft. A transport section and a sheet feeder are then inserted into the box machine. The transport section comprises transport wheels driven by the drive shaft which engage a sheet to transport it to the box machine without crushing. The sheet feeder comprises feed wheels driven by a servo motor for feeding the lowermost sheet of a stack to the transport section. A feed interrupter is movable from a raised stop-feed position to a lowered feed position by cams rotated by a servo motor. A controller coordinates the velocity of the feed wheels and position of the feed interrupter. Retrofitted machines eliminate the need to increase Edge Crush Test ratings of sheets from the corrugator 15% to 20% greater than printed in the certificate stamp.

Not Applicable.

Not Applicable.

BACKGROUND OF THE INVENTION

Prior Art

The following is a tabulation of some prior art that presently seems relevant:

This invention relates to the manufacture of corrugated paperboard boxes in compliance with the National Motor Freight Classification Item 222 and the National Railroad Freight Committee's Uniform Freight Classification Rule 41 standards for box manufacture.

This invention particularly relates to the manufacturing of corrugated paperboard boxes with Edge Crush Test certification under these standards

Corrugated paperboard boxes are used to safely ship products throughout the United States and the world. Items ranging from lightweight and small, to heavy and large are safely transported in corrugated paperboard boxes.

The ability to safely transport this large range of items in paperboard boxes is assured because corrugated paperboard boxes are manufactured to comply with the National Motor Freight Classification Item 222 and the National Railroad Freight Committee's Uniform Freight Classification Rule 41 standards for box manufacture.

To comply with the standards, corrugated paperboard boxes are required to be tested by either an Edge Crush Test, or a Burst Test to certify their durability and strength. A small square is cut from a finished box and the appropriate test is performed. The resulting Edge Crush Test rating in lbs./inch, or the Burst Test rating in lbs. is printed in a box-makers certificate on each box, certifying the strength of the finished boxes, as required by Rule 41 of the Uniform Freight Classification of the railroads and the nearly identical Item 222 of the National Motor Freight Classification.

Historically, for nearly a century, the only standard test was the Burst (Mullen) Test, which is indirectly related to a carton's ability to withstand external or internal forces to contain and protect a product during shipment, and is related to the rough handling of individual boxes. The Burst Test mandates a “minimum combined weight of facings”, thereby offering no opportunity to save corrugated paperboard material. Burst Test ratings are not degraded when the combined board is crushed.

In 1991 an alternative Edge Crush Test was approved that is now the dominant test used in the industry. Edge Crush Test is a true performance test directly related to the stacking strength of a box. By providing an alternative to the Burst test mandate for a minimum combined weight of facings, Edge Crush Testing allows the use of lighter weight, less costly board without sacrificing stacking strength. Edge Crush Test ratings, however, are degraded when the combined board is crushed.

Since 1991, corrugated paperboard box manufacturers have manufactured boxes with either a Burst test certification, or an Edge Crush Test certification, depending on the specific shipping requirements.

In a box making plant corrugated paperboard is produced on a corrugator. The board continues through the corrugator and is cut into predetermined sheet sizes, stacked, and delivered in stacks to converting machinery to be converted into boxes.

Existing converting machinery crushes the corrugated paperboard during converting machine operations. The Burst Test ratings of Burst Test certified boxes are not degraded when corrugated paperboard is crushed by existing converting machinery. Edge Crush Test ratings, however, are degraded when the corrugated paperboard is crushed by existing converting machinery.

Because the Burst ratings are not degraded when corrugated paperboard is crushed by converting machinery, and Edge Crush Test ratings are degraded when corrugated paperboard is crushed by converting machinery, two different manufacturing methods are used for Burst Test and Edge Crush Test certified boxes produced on existing converting machinery.

In the manufacturing of Burst certified boxes, sheets from the corrugator are supplied to converting machinery with a Burst rating that is the same as the Burst rating printed on the certificate stamp, because Burst ratings are not degraded when corrugated paperboard is crushed by converting machinery

In the manufacturing of Edge Crush Test certified boxes, however, it is industry wide recommended practice to supply sheets from the corrugator to converting machinery with an Edge Crush Test rating that is from 15% to 20% percent greater than the Edge Crush Test value printed on the certificate stamp, in order to compensate for Edge Crush Test converting machinery degradation, because Edge Crush Test ratings are degraded when corrugated paperboard is crushed by converting machinery.

Increasing the Edge Crush Test rating of sheets from the corrugator from 15% to 20% percent, currently necessary to compensate for Edge Crush Test converting degradation on existing converting machinery, increases fiber use and increases the cost of Edge Crush Test certified boxes. Eliminating Edge Crush Test converting machinery degradation would eliminate the need to increase the Edge Crush Test rating of sheets from the corrugator from 15% to 20% percent, and would benefit the customer, the converter, the corrugated box industry, and the environment.

In a box making plant the sheets produced on the corrugator are delivered in stacks to the converting machinery to be converted into boxes.

In the corrugated paperboard industry it is known to use lead edge sheet feeders at the beginning of converting machinery to feed single sheets from a stack to converting operations. Modern sheet feeders of conventional design, for example, as disclosed in U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella use vacuum assisted feeding elements, such as feed wheels, to transfer the sheet from beneath the stack of sheets to a feed roll nip between a pair of feed rolls for taking over feeding of each sheet from the feed wheels and then feeding the sheet to downstream operations. The feed roll nip is an essential component of these sheet feeders.

The feed rolls are arranged one on top of the other and are spaced slightly apart from each other. The feed rolls must be spaced apart a distance which is smaller than the thickness of the sheet being fed, to press against the sheet and generate enough frictional grip to pull the sheet from beneath the stack and transfer the sheet to downstream converting operations. The small opening between the upper and lower feed rolls through which the sheet must pass is commonly known as the “feed roll nip”.

It is an essential part of conventional sheet feeder operation to make the opening at the feed roll nip small enough to ensure that the sheet is under control for transferring to subsequent machine operations. It is common with conventional feeders to make the feed roll nip between the upper and lower feed rolls so small that the corrugated layer of the sheet is crushed by the feed rolls as it is gripped by them, resulting in Edge Crush Test degradation.

The feed roll nip is recognized in the industry as the major cause of undesirable Edge Crush Test converting degradation.

Retrofitting existing converting machines to eliminate the feed roll nip would eliminate the major source of Edge Crush Test converting degradation, and eliminate the need to supply converting machines with sheets from the corrugator with an Edge Crush Test rating that is from 15% to 20% percent greater than the Edge Crush Test value printed on the certificate stamp, in order to compensate for Edge Crush Test converting degradation. Retrofitting existing converting machines to eliminate the feed roll nip would be a practical and cost effective way to eliminate this wasteful practice.

Eliminating the feed roll nip presents a problem, however, in that the feed roll nip is the nip between the upper and lower feed roll on all existing conventional converting machines, and the lower feed roll is used to drive the main gear train on all existing conventional converting machines. Eliminating the lower feed roll would eliminate the drive for the main gear train of the converting machine.

Eliminating the feed roll nip presents an additional problem, in that the feed roll nip is an essential component of conventional sheet feeders. The feed roll nip is necessary to pull the trailing portion of the sheet from the sheet feeder.

It has been proposed to use lead edge sheet feeders with no feed rolls, as disclosed in U.S. Pat. No. 3,941,372 to Matsuo, U.S. Pat. No. 4,236,708 to Matsuo, U.S. Pat. No. 5,006,042 to Park, U.S. Pat. No. 5,451,042 to Cuir, U.S. Pat. No. 6,543,760 to Andrien, U.S. Pat. No. 7,621,524 to Levin, U.S. Pat. No. 5,228,674 to Holmes and U.S. Pat. No. 5,048,812 to Holmes to solve the problem of crushing the corrugated paperboard sheets by the feed roll nip. These disclosures, however, fail to address how these lead edge sheet feeders with no feed rolls can be retrofitted into existing converting machines. Converting machines with feed rolls have been manufactured from the early nineteen hundreds until the present time. Replacing the vast number of existing converting machines that have feed rolls with new converting machines that have no feed rolls, to solve the problem of crushing the corrugated paperboard sheets by the feed roll nip, is not a practical solution to the problem, because of the enormous capital cost of new converting machines that would be involved.

Emba Machinery AB, Orebro, Sweden, a manufacturer of converting machinery, offers new converting machines with no feed rolls (model 245 QS Ultima), that include a sheet feeder with no feed roll nip, as disclosed in U.S. Pat. No. 7,621,524 to Levin. Emba Machinery has reported that, with this converting machine, there is no longer any need to increase the ECT value of sheets from the corrugator by 15% percent in order to compensate for ECT converting degradation, because the feed roll nip has been eliminated. Emba Machinery does not offer a machine retrofit, however, for the vast number of existing converting machines operating with a feed roll nip. U.S. Pat. No. 7,621,524 to Levin fails to disclose how such lead edge sheet feeders, with no feed rolls, can be retrofitted into existing box converting machines.

Accordingly, there is a need for a practical and cost effective method for retrofitting the vast number of existing box converting machines to eliminate the feed roll nip and thereby end the wasteful practice of increasing the incoming Edge Crush Test rating of sheets from the corrugator by 15% to 20% percent in order to compensate for Edge Crush Test converting degradation, and a non-crush sheet feeder comprising a non-crush constant speed transport section and a variable speed sheet feeder section for use with such retrofitted corrugated paperboard converting machines.

BRIEF SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a simple, practical, and cost effective method and apparatus for retrofitting existing box converting machines to eliminate a feed roll nip and thereby end the wasteful practice of increasing the incoming Edge Crush Test rating of sheets from the corrugator by 15% to 20% percent in order to compensate for Edge Crush Test converting degradation.

Another object of the present invention is to provide a non-crush sheet feeder comprising a non-crush constant speed transport section and a variable speed sheet feeder section for use with such retrofitted corrugated paperboard converting machines.

Described herein is a device and method for retrofitting existing corrugated paperboard converting machines for ending the industry wide wasteful practice of manufacturing corrugated paperboard sheets on the corrugator with Edge Crush Test ratings that are from 15% to 20% percent greater than the Edge Crush Test rating printed in the box-maker's certificate, in order to compensate for the degradation of the Edge Crush Test rating of the box, caused by existing converting machinery.

The device and method disclosed herein eliminates the converting machine feed roll nip that is the cause of increasing the incoming Edge Crush Test rating of sheets from the corrugator by 15% to 20% percent to compensate for Edge Crush Test converting degradation.

The advantages described above are achievable whereby a conventional corrugated paperboard box converting machine comprising feed rolls, a feed roll nip, and a conventional sheet feeder is retrofitted by first removing the conventional sheet feeder, and by removing the feed rolls.

A machine drive shaft, a non-crush sheet feeder comprising a variable speed sheet feeder section, and a non-crush constant speed vacuum transport section, is then inserted into the box converting machine.

The variable speed sheet feeder section may comprise a plurality of variable speed feed wheels which engage the lowermost sheet of a stack of sheets to feed it to the constant speed vacuum transport section. The variable speed feed wheels protrude above the top of a vacuum chamber for holding the sheet against the feed wheels.

The non-crush constant speed vacuum transport section may comprise a plurality of constant speed vacuum transport wheels which engage the sheet to transport it to the box converting machine without crushing. The constant speed transport wheels protrude above the top of a vacuum chamber for holding the sheet against the transport wheels.

Corrugated paperboard box converting machines so retrofitted eliminate the existing feed roll nip for ending the wasteful practice of increasing the incoming Edge Crush Test value of sheets from the corrugator by 15% to 20% percent in order to compensate for Edge Crush Test converting degradation caused by the eliminated feed roll nip.

DETAILED DESCRIPTION

Prior Art

Referring to the drawings in detail, there is illustrated in schematicsFIG. 1AandFIG. 2A, a box converting machine1of the prior art, comprising a Feeding section2, a Printing section3, and a Cutting-Scoring section4. Feeding section2comprises an upper feed roll5, a lower feed roll6, a feed roll nip7, a feed gate8, and a conventional variable speed sheet feeder10adapted to feed sheet23to a feed roll nip7. Conventional sheet feeder10may be as described in U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella. Conventional sheet feeder10comprises a plurality of variable speed feed wheels78protruding above a vacuum chamber38with an intense vacuum for feeding sheet23, the lowermost sheet of stack22, past feed gate8and to feed roll nip7between upper feed roll5and lower feed roll6.

Referring toFIG. 2A, a section through the upper feed roll5and lower feed roll6of a converting machine1of the prior art is shown. Concentric bearing housings19and21are supported by side frames of feed section2. Lower feed roll6is supported for rotation in concentric bearing housings19and21. Eccentric bearing housings18and20are supported for rotation in side frames of feed section2. Upper feed roll5is supported for rotation in eccentric bearing housings18and20. Machine drive pulley14is fixed to lower feed roll6to be rotated by a machine drive motor, not shown. Machine drive gear15is fixed to lower feed roll6. Machine drive gear15is the drive gear for the main gear train of box machine1through a gear mesh not shown. Drive gear15also meshes with gear16for driving upper feed roll5through permanent mesh assembly17. The opening at nip7is adjustable to grip sheet23by rotation of eccentric bearing housings18and20by a control shaft not shown. A proper mesh between gears15and16is maintained during adjustment by permanent mesh assembly17. Permanent mesh assembly17is a modified Oldham coupling, well known by those in the industry.

Referring now toFIG. 1AandFIG. 2A. In the operation of one prior art converting machine1feed cycle, a machine drive motor, not shown, rotates machine drive pulley14, lower feed roll6and machine drive gear15, to drive the main gear train of converting machine1through a gear mesh with gear15, not shown. Machine drive gear15additionally meshes with gear16to rotate upper feed roll5through permanent mesh assembly17.

Referring toFIG. 1A, sheet23and sheet stack22are supported by a variable speed sheet feeder10comprising driven variable speed feed wheels78. At the beginning of a machine1operating cycle, variable speed feed wheels78engage lowermost sheet23of stack22and drive sheet23to nip7between upper feed roll5and lower feed roll6of box converting machine1. Below sheet23is a feed interrupter80moveable between a raised stop-feed position wherein variable speed feed wheels78are spaced from sheet23and a lowered feed position wherein sheet23engages variable speed feed wheels78and is thereby driven by variable speed feed wheels78. Below feed interrupter80is a vacuum chamber79for generating an intense vacuum on the underside of sheet23for holding sheet23against rotating variable speed feed wheels78when feed interrupter80is in its lowered position. Variable speed feed wheels78and the movement of feed interrupter80are indirectly driven by the main gear train, not sown, of converting machine1.

In the operation of one converting machine1operating cycle, with feed interrupt feed interrupter80in its lowered feed position, variable speed feed wheels78contact sheet23and drive sheet23to nip7between feed rolls5and6, at which point feed roll nip7grips sheet23to drive sheet23and continues to drive sheet23at a constant speed until the trailing edge of sheet23passes feed roll nip7.

Prior to the trailing edge of sheet23contacting the most upstream feed wheel78, feed interrupter80rises to its raised position to prevent contact between variable speed feed wheels78and the next sheet in stack22.

When feed interrupter80is in a raised position, the intense vacuum of vacuum chamber38holds the trailing portion of sheet23against feed interrupter80.

In order for nip7to grip sheet23with sufficient frictional traction to pull the trailing edge of sheet23from feed interrupter80against the intense vacuum force of vacuum chamber79, the opening at nip7must be made smaller than the thickness of sheet23. The corrugated medium of sheet23is thereby crushed as it passes through nip7. Crushing the corrugated medium of the sheet23results in Edge Crush Test degradation.

The general construction and operation of the feed wheels78, the raising and lowering of feed interrupter80, the drive apparatus for feed wheels78, the application of vacuum, and the timing of these movements is described and illustrated in greater detail in U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella, which are incorporated by reference.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Detailed Description of Converting Machine Retrofit

Referring now toFIG. 1B,FIG. 2B,FIG. 1C,FIG. 2C,FIG. 2D, andFIG. 2E, in accordance with one aspect of the present invention, there is illustrated a method for retrofitting conventional converting machine1to eliminate feed roll nip7and its associated Edge Crush Test degradation.

Referring now toFIG. 1BandFIG. 2B, in which conventional converting machine1is shown after the initial retrofitting steps of: removing feed gate8, removing upper feed roll5, removing bearing housings18, and20, removing lower feed roll6, and inserting drive shaft9.

Referring now toFIG. 2B, a section through drive shaft9is shown. Concentric bearing housings19and21are supported by side frames of feed section2. Drive shaft9is supported for rotation in concentric bearing housings19and21. Machine drive pulley14is fixed to drive shaft9for rotation by a machine drive motor, not shown. Machine drive gear15is fixed to drive shaft9. Machine drive gear15is the drive gear for the gear train of box machine1through a gear mesh not shown.

Referring now toFIG. 1CandFIG. 2C,FIG. 3C, andFIG. 4Cin which conventional converting machine1is shown after the retrofitting steps of: inserting a variable speed feed section13adapted to operate with a vacuum transport section, and constant speed vacuum transport section12, and by inserting feed gate8into feed section2of box converting machine1.

Referring now toFIG. 2C, a section through drive shaft9of retrofitted converting machine1is shown. Concentric bearing housings19and21are supported by side frames of feed section2. Drive shaft9is supported for rotation in concentric bearing housings19and21. Machine drive pulley14is fixed to drive shaft9to be rotated by a machine drive motor, not shown. Machine drive gear15is fixed to drive shaft9. Machine drive gear15is the drive gear for the gear train of box machine1through a gear mesh not shown.

Drive shaft9passes through constant speed transport section12and gear case33. Constant speed transport section12is supported by feeder section2side frames through support plates31and32. Constant speed transport section drive gear30is fixed to drive shaft9. Transport wheels24are fixed to drive shaft9and protrude above vacuum chamber27. An intense vacuum pressure is generated in vacuum chamber27by a vacuum blower, not shown, for communicating intense vacuum pressure to the underside of sheet23, through openings in vacuum chamber cover28, for generating an intense vacuum on the underside of sheet23for holding sheet23against constant speed transfer wheels24and25.

Referring toFIG. 1C, andFIG. 3C, a section through transport wheels24is shown. Transport wheel shaft26is supported for rotation in support plates31and32. Driven gear34is fixed to shaft26for driving shaft26.

Referring toFIG. 4C, a drive train for driving transport wheels25is shown. Transport section drive gear30is fixed to drive shaft9for rotating transport wheels25through idler gear35, and driving shaft26.

Referring now toFIG. 1C,FIG. 2C,FIG. 3C, andFIG. 4C. In the operation of one converting machine1feed cycle, a machine drive motor, not shown, rotates machine drive pulley14, drive shaft9, and machine drive gear15, to drive the main gear train of converting machine1through a gear mesh with gear15, not shown.

Referring toFIG. 1C, sheet23and sheet stack22are supported by a variable speed sheet feeder section13adapted to operate with a constant speed transport section comprising driven variable speed feed wheels41,42,43,44. At the beginning of a machine1operating cycle, variable speed feed wheels41,42,43,44engage lowermost sheet23of stack22and drive sheet23to cover constant speed transfer section12. Below sheet23is a feed interrupter49moveable between a raised no-feed position wherein variable speed feed wheels41,42,43,44are spaced from sheet23and a lowered feed position wherein sheet23engages variable speed feed wheels41,42,43,44and is thereby driven by variable speed feed wheels41,42,43,44. Below feed interrupter49is a vacuum chamber38for generating an intense vacuum on the underside of sheet23for holding sheet23against rotating variable speed feed wheels41,42,43,44when feed interrupter49is in its lowered position.

In the operation of one converting machine1operating cycle, with feed interrupter49in its lowered position, variable speed feed wheels41,42,43,44feed sheet23past feed gate8and to cover constant speed vacuum transport section12, at which point constant speed transport wheels24,25acquire maximum vacuum traction and drive sheet23and continue to drive sheet23at constant speed until the trailing edge of sheet23pass constant speed transport wheels25.

Feed wheels41,42,43,44stop feeding sheet23when the trailing edge of sheet23reaches the most upstream feed wheel44, to prevent feed wheel41,42,43,44from contacting the next sheet of stack22. At this point in the feed cycle, transport of sheet23is continued by constant speed vacuum transport wheels24and25.

The intense vacuum on the underside of sheet23for holding sheet23against constant speed vacuum transfer wheels24and25provides sufficient frictional traction to pull the trailing portion of sheet23from feed interrupter49against the intense vacuum force of vacuum chamber38.

The corrugated medium of sheet23is not crushed as it is transported downstream by vacuum transport wheels24and25. Because sheet23is not crushed, there is no Edge Crush Test degradation.

Prior art variable speed sheet feeders that were originally designed to feed sheets to a feed roll nip such as U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella, with the general construction and operation of feed wheels, raising and lowering of a feed interrupter, a variable speed drive apparatus for driving feed wheels, the application of vacuum, and the timing of these movements could presumably be modified to instead operate with a constant speed vacuum transport section described above. One embodiment of an improved variable speed sheet feeder section13that is particularly more suited for retrofitting a conventional converting machine is described below.

Detailed Description of One Embodiment of a Sheet Feeder for Retrofitting a Conventional Converting Machine:

Referring now toFIG. 3, andFIG. 4, there is shown one embodiment of a non-crush constant speed vacuum transport section12and a variable speed sheet feed section13.

Detailed Description of Non-Crush Constant Speed Vacuum Transport Section12:

Refer toFIG. 3,FIG. 4, andFIG. 7, cover28forms the top of a vacuum chamber27in which a vacuum is produced through vacuum duct29communicating through the bottom of the chamber27with a vacuum blower, not shown. Vacuum chamber27is supported by vertical supports31and32which are suitable fixed to crossties of feed section2, not shown. Cover28includes vacuum holes36for communicating the vacuum of vacuum chamber27to the underside of sheet23.

Referring toFIG. 2C, drive shaft9is supported to for rotation by machine drive pulley14in the side frames of feed section2by concentric bearing housings19and20, and passes through support plates31and32and vacuum chamber27. Referring toFIG. 3andFIG. 12, a plurality of evenly spaced transport wheels24are fixed to drive shaft9and protrude through openings in vacuum chamber cover28. The diameter of transport wheel24is equal to the diameter of replaced lower feed roll6, for matching the surface speed of converting machine1.

A plurality of evenly spaced transport wheels25are fixed to shaft26and protrude through openings in vacuum chamber cover28. Shaft26is supported for rotation in support plates31and32.

Referring toFIG. 11,FIG. 12, andFIG. 14, drive shaft9drives transport wheels25through drive gear30, idler gear35, and driven gear34within gear case33. The diameter of transport wheel25relative to the diameter of transport wheel24is equal to the ratio of the number of teeth on gear34to the number of teeth of gear30, for matching the surface speed of converting machine1. Transport wheels24and25are thereby driven by drive shaft9at the surface speed of the box machine1.

Transport wheels24and25have a high friction surface for engaging the underside of sheet23for positively driving sheet23to printing section3.

Referring toFIG. 11, resolver72is driven by drive shaft9through gears30,35,34, shaft26and gears73and74, for communicating with controller77for tracking the speed and position of the operating elements of box machine1, which is driven by drive shaft9through drive gear15(FIG. 2C).

Detailed Description of Variable Speed Sheet Feed Section13:

Covers39,55and vacuum chamber38define a chamber in which a vacuum is produced through vacuum duct67communicating with a vacuum blower, not shown. Cover55includes openings surrounding the protruding feed wheels for communicating the vacuum of vacuum chamber27to the underside of sheets23. Vacuum chamber38is supported by vertical support plates31and32which are fixed to crossties, not shown, of feed section2.

The front, or leading edge of sheet stack22is located by a vertical feed gate8and supported by support wheel assembly40. The gap between feed gate8and support wheel assembly40is adjustable to permit passage of only a single sheet23.

The first set (plurality) comprises shafts45with a plurality of feed wheels41and shaft47with a plurality of feed wheels43. Feed wheels41and43are mounted in alignment.

The second set (plurality) comprises shafts46with a plurality of feed wheels42and shaft48with a plurality of feed wheels44. Feed wheels42and44are mounted in alignment, but staggered with respect feed wheels41and43, for conserving space in the feed direction.

Referring toFIG. 4, there are two inline feed wheels, either41and43, or42and44for each two inline transfer wheels24and25, whereby constant speed transport section12and variable speed feed section13each provide equal traction by driving sheet23with two in-line wheels.

Referring toFIG. 3,FIG. 14andFIG. 15, servo motor70, for driving the rotation of feed wheels41,42,43, and44is mounted to gear case63and supported by support plate31. Drive gear58is fixed to the output shaft of servo motor70and drives idler gears57and gears56. Gears56drive shafts45,46,47and48and thereby drive feed wheels41,42,43, and44.

Rotation of servo motor70is controlled by programmable controller77.

Referring toFIG. 4,FIG. 7,FIG. 8,FIG. 9,FIG. 10, andFIG. 10A, supported for vertical movement between a raised and lowered position is a plurality of feed interrupters49each comprising bracket66, and wheels65. When feed interrupters49are in a lowered position they cannot contact sheet23and sheet23is supported by feed wheels41,42,43, and44. When feed interrupters49are in a raised position, they contact the bottom of sheet23and support sheet23and stack22out of contact with feed wheels41,42,43, and44, to interrupt the feed of sheets23.

An interrupt cover55is fixed to brackets66of feed interrupters49, with openings through which feed wheels41,42,43, and44protrude. Interrupt cover55along with cover39form the top of vacuum chamber38in which a vacuum is produced through vacuum duct67(FIG. 7) connecting through the bottom of chamber38with a vacuum blower, not shown. Vacuum chamber38is supported on vertical supports31and32which are suitable fixed to crossties (not shown) of feed section2. The openings through which feed interrupters49and feed wheels41,42,43, and44protrude communicate the vacuum of vacuum chamber38to the underside of sheet23.

With continuing reference toFIG. 3,FIG. 4,FIG. 7,FIG. 10,FIG. 10A,FIG. 13,FIG. 14, andFIG. 16, the mechanism by which feed interrupters49are moved vertically between an up and down position is shown.

Referring toFIG. 3,FIG. 4,FIG. 7andFIG. 10,FIG. 10AandFIG. 13, andFIG. 16, a plurality of feed interrupters49are supported by interrupt frame50. Frame50supports eight sets of a pair of vertically arranged guide rollers51. Each set of vertically arranged pair of guide rollers51ride in eight vertical guides64fixed to vacuum chamber38. There are two sets of guide rollers51fixed to each side and to each end of frame50. Frame50and feed interrupters49are, thereby, confined to vertical movement.

Frame50and feed interrupters49are supported for vertical movement by four lower guide rollers51designated as51-1,51-2,51-3, and51-4fixed to the ends of frame50. Guide rollers51-1,51-2,51-3, and51-4are supported on the surface of four cams52-1,52-2,52-3, and52-4which are fixed to two parallel cam shafts53-1and53-2. Cam shafts53-1and53-2are supported for rotation in support plates31and32. Rotation of cam shafts53-1and53-2will result in vertical movement of frame50and feed interrupters49.

Referring toFIG. 10,FIG. 10A,FIG. 13, andFIG. 14, cam servo motor69is mounted to motor support71fixed to support plate32. The output shaft of servo motor69is coupled to cam drive shaft53-1by coupling68. Cam shaft53-1is supported for rotation in support plates31and32. Cams52-1and52-2are fixed to cam shaft53-1. Drive gear60-1is fixed to drive shaft53-1and drives idler gear61(FIG. 14) and drive gear60-2fixed to cam drive shaft53-2. Cams52-3and52-4are fixed to drive shaft53-1. Cam shaft53-2is supported for rotation in support plates31and32. Cams52-1,52-2,52-3, and52-4are mounted in synchronized alignment.

Rotation of servo motor69will thereby rotate cams52-1,52-2,52-3, and52-4in synchronism. The contour of cams52-1,52-2,52-3, and52-4is such that a first one-half revolution of the cams will raise frame50and feed interrupters49from a lowered, feed, position to a raised, stop-feed, position due to the surface contact between guide rollers51-1,51-2,51-3, and51-4and cams52-1,52-2,52-3, and52-4.

A second one-half revolution of the cams52-1,52-2,52-3, and52-4will lower frame50and feed interrupters49from a raised, stop-feed, position to a lowered, feed, position due to the surface contact between guide rollers51-1,51-2,51-3,51-4and cams52-1,52-2,52-3, and52-4.

The magnitude of movement of feed interrupters49from the lowered position to the raised position in practice may be approximately 0.125″ for 180 degree rotation of the cams52-1,52-2,52-3, and52-4, providing a gentile and smooth transition from raised and lowered positions.

When feed interrupters49are in the lowered feed position, sheet23engages feed wheels41,42,43, and44to be positively driven under feed gate8and to constant speed transport section12.

When feed interrupters49are in the raised, stop-feed position, feed interrupters49contact and support sheet23and stack22out of engagement with feed wheels41,42,43, and44to stop the feeding of sheet23, and to prevent contact of feed wheels41,42,43, and44with the next lowermost sheet in stack22.

Rotation of servo motor69is controlled by programmable controller77(FIG. 20).

Referring toFIG. 20,FIG. 11andFIG. 14, Drive shaft9drives the gear train of box machine1through drive gear15, and resolver72through a drive train of drive gear30, idler35, gear34, shaft26, gear73, and gear74, whereby resolver72may track and communicate the relative rotation and velocity of a main cylinder of the box machine, which may be a print cylinder, a die-cutting cylinder, or a slotting head cylinder, to programmable controller77(FIG. 20). Feed wheel servo motor70encoder communicates the rotation and velocity of feed wheels41,42,43, and44to programmable controller77(FIG. 20). Feed interrupt cam drive servo motor69encoder communicates the position of feed interrupt cams feed wheels41,42,43, and44to programmable controller77(FIG. 20). Operator input82communicates input such as the length of sheet23and regular feed, to programmable controller77. Programmable controller77thereby calculates and controls the rotation of feed wheels41,42,43, and44through feed wheel servo motor70, and the position of feed interrupters49through feed interrupt cam drive servo motor69.

Referring toFIG. 1C, at the time of installation variable speed sheet feeder section13is configured for operation to match the repeat length of box machine1. The repeat length of a box machine is the circumferential length of a main cylinder of the box machine which cylinder may be a printing cylinder, a die cutting cylinder, or a slotting head. In general, a box machine repeat length may any length, but generally can be 24, 35, 36, 37, 50, 66, 96 inches, for instance, or other designated repeat lengths. A typical U.S. box plant may have box machines with 35, 50 and 66 inch repeat lengths, for instance.

Conventional corrugated paperboard sheet feeders such as U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella operate at one predetermined repeat length. A different model variable speed sheet feeder is required to be retrofitted to box machines with 35, 50, and 66 inch repeat lengths, for instance.

A variable speed sheet feeder section13of the present invention, in comparison, can be programmed to operate with any machine repeat size, providing economy in manufacturing.

Referring toFIG. 20, during installation of variable speed sheet feeder13, programmable controller77is programmed to operate with the repeat length of box machine1. After the initial programming of programmable controller77, the feeder may be put into production.

It is known that corrugated paperboard sheet feeders such as U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella may provide different modes of operation, such as, feed one sheet per feed cycle (regular feed), feed two sheets per feed cycle (dual feed), feed one sheet for two feed cycles (skip feed), feed one sheet on demand (during set-up), and stop feed on demand (in an emergency). All of these prior art disclosures require additional mechanical components for each additional mode of operation, whereby each additional mode of operation adds manufacturing expenses.

Referring toFIG. 20, for comparison, programmable controller77may be programmed to provide different modes of operation, such as, feed one sheet per feed cycle (regular feed), feed two sheets per feed cycle (dual feed), feed one sheet for two feed cycles (skip feed), feed one sheet on demand (during set-up), and stop feed on demand (in an emergency). Each additional mode of operation requires no additional mechanical components, and no increased manufacturing expenses.

Machine operation begins with the operator entering the sheet size and selects feeding one sheet for one box machine cycle (regular feed), for instance, at operator station82(FIG. 20). Vacuum blowers, not shown, are actuated for maintaining a constant vacuum pressure in vacuum chambers27, and38of sheet feed section13and vacuum transport section12(FIG. 3) to be communicated to the underside of sheet23.

Box machine drive motor, not shown, is activated driving machine drive pulley14, drive shaft9, constant speed transfer wheels24, transport section drive gear30, and machine drive gear15. Machine drive gear15drives the main gear train of the box machine through a gears mesh, not shown, at a constant speed. (FIG. 2C).

Referring toFIG. 2CandFIG. 14,FIG. 11, andFIG. 12, drive shaft9drives constant speed transport wheels25through the gear mesh between transport drive gear30, idler gear35, and gear34fixed to transport wheel shaft26, whereupon constant speed transfer wheels24and25rotate at constant speed.

Referring toFIG. 14andFIG. 15, feed wheel servo motor70is activated to be controlled by programmable controller77(FIG. 20) for driving feed wheels44,42,43, and44through the mesh of drive gear58, idlers57, and gears56, thereby driving shafts45and47(FIG. 5) and shafts46and48(FIG. 6).

Referring toFIG. 14andFIG. 10, cam drive servo motor69is activated to be controlled by programmable controller77(FIG. 20) for rotating feed interrupt cams52-2,52-2,52-3, and52-4through rotation of shaft53-1and the gear mesh of drive gear60-1, idler61, and gear60-2, thereby driving shafts53-1and53-2(FIG. 15) to rotate cams52-2,52-2,52-3, and52-4in synchronism to raise and lower feed interrupters49(FIG. 10andFIG. 10A)

Referring toFIG. 17, a diagram illustrating the velocity of feed wheels41,42,43, and44relative to the velocity of box machine1, feeding one sheet for one box machine cycle (regular feed), and the relative position of feed interrupters49is shown.

The direction of feed is illustrated inFIG. 4by arrow76.

Referring toFIG. 17andFIG. 17A, schematic17A illustrates the conditions at the beginning of a feed cycle. Constant speed transfer wheels24and25rotate at machine speed. Feed wheels41,42,43, and44are at zero velocity and begin an acceleration segment from zero velocity to 100% of the velocity of the box machine. Feed interrupters49are in a down, feed, position. Feed wheels41,42,43, and44contact sheet23with vacuum traction.

Referring toFIG. 17andFIG. 178, constant speed transfer wheels24and25rotate at machine speed, feed wheels41,42,43, and44end the acceleration segment, the leading edge of sheet23contacts constant speed transfer wheels25, feed wheels41,42,43, and44begin a constant speed segment. Feed interrupters49are n the down, feed, position. Feed wheels41,42,43, and44contact and drive sheet23with vacuum traction.

Referring toFIG. 17andFIG. 17C, constant speed transfer wheels24and25rotate at machine speed, the leading edge of sheet23covers vacuum chamber27whereby constant speed transfer wheels24, and25acquire maximum vacuum traction, and drive sheet23. Feed interrupters49are in the down, feed, position. Feed wheels41,42,43, and44contact and drive sheet23with vacuum traction and continue at constant speed. Sheet23is driven by a plurality of wheels41,42,43, and44, and an equal plurality of wheels24and25(FIG. 4).

Referring toFIG. 17andFIG. 17E, constant speed transfer wheels24and25rotate at machine speed, sheet23covers vacuum chamber27whereby constant speed transfer wheels24, and25drive sheet23with maximum vacuum traction. The trailing edge of sheet23has reached feed wheel41. Feed interrupters49are in the up, stop-feed, position. Feed wheels41,42,43, and44do not contact sheet23. Feed wheels41,42,43, and44end their deceleration segment, and dwell at zero velocity until the end of the feed cycle. Feed interrupters49are in the up, stop-feed, position and prevent contact between feed wheels41,42,43, and44and the next lowermost sheet in stack22. Sheet23is driven by transfer wheels24and25.

Referring toFIG. 4,FIG. 17andFIG. 17F, constant speed transfer wheels24and25rotate at machine speed, sheet23covers vacuum chamber27whereby constant speed transfer wheels24, and25drive sheet23with maximum vacuum traction. The trailing edge of sheet23has passed sheet stack22. Feed interrupters49are in the down, feed, position. Feed wheels41,42,43, and44contact the lowermost sheet of stack22, and dwell at zero velocity until the end of the feed cycle. Sheet23is driven by transfer wheels24and25.

Referring toFIG. 18, a diagram showing the relationship between feed wheels41,42,43,44, and feed interrupters49during a dual feed operation is shown. Two sheets23are fed during one cycle of the box machine in this mode of operation. Dual feed may be used when the length of sheet23is less than one-half the repeat length of the box machine. Dual feeding doubles the production rate of such sheets relative to feeding one sheet23per feed cycle.

Controller77may be configured to control feed wheels41,42,43,44, and feed interrupters49to operate in a dual feed mode. No additional mechanical components are required, as on conventional sheet feeders. The machine operator need only select dual feeding at operator input station82to access this mode of operation.

Referring toFIG. 19, a diagram showing the relationship between feed wheels41,42,43,44, and feed interrupters49during a skip-feed operation of the present invention is shown. One sheet23is fed during two cycles of the box machine in this mode of operation.

Skip feed may be used when the length of sheet23is greater than the repeat length of the box machine1. Skip feeding halves the production rate of such sheets relative to feeding one sheet23per feed cycle, but enables sheets23greater than the repeat length of the box machine to be processed.

Controller77may be configured to control feed wheels41,42,43,44, and feed interrupters49to operate in a skip feed mode. No additional mechanical components are required. The machine operator need only select skip feeding at operator input station82to access this mode of operation.

Controller77may be configured to control feed wheels41,42,43,44, and feed interrupters49to feed one sheet per feed cycle, two sheets per feed cycle, one sheet for two feed cycles, emergency stop feed, and to feed individual sheets on demand during set-up, all with no additional mechanical machine elements. The machine operator needs only to select the mode of operation and the size of sheet23at operator input station82.

Although, a specific improved embodiment is shown, the apparatus of corrugated paperboard sheet feeders such as U.S. Pat. No. 5,184,811 to Sardella, U.S. Pat. No. 6,824,130 to Sardella, U.S. Pat. No. 4,896,872 to Sardella, and U.S. Pat. No. 4,828,244 to Sardella, or other similar sheet feeders may be modified and employed to operate in tandem with the machine retrofit described above.

It should be understood that although feed wheels41,42,43, and44and transport wheels24and25have been used in the embodiment shown and described above, endless drive members (not shown) such as belts may be employed as well.

It will therefore be seen that the present invention allows sheets to be fed eliminating feed roll nip crush, thereby eliminating the need to supply sheets from the corrugator to converting machinery with an Edge Crush Test rating that is from 15% to 20% percent greater than the Edge Crush Test value printed on the certificate stamp, in order to compensate for Edge Crush Test converting machinery degradation.

Although specific versions and embodiments of the present invention have been shown and described, it will be understood that the scope of the invention is not limited to the specific embodiments but rather will be indicated in the claims appended.