US3871564A

US3871564A - Method and apparatus for guiding and tensioning a web during changeover from a web of one width to a web of another width

Info

Publication number: US3871564A
Application number: US432454A
Authority: US
Inventors: David Middleman
Original assignee: Koppers Co Inc
Current assignee: United Container Machinery Group Inc
Priority date: 1972-03-20
Filing date: 1974-01-11
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18

Abstract

A method of applying vacuum tension to a web during changeover from a web of one width to a web of another width comprising the steps of advancing the web along a path of advance; applying vacuum tension to the web substantially across the entire web; applying the vacuum tension to a centermost portion of the web prior to changing the width of the web, the centermost portion being equal to or narrower then the narrowest web to be advanced; and thereafter applying vacuum tension substantially across the entire width of the web then being advanced. The preferred apparatus for performing the method is a web guiding and tensioning apparatus of the type including a vacuum chamber for applying subatmospheric pressure to a smooth side of the web for tensioning the web and a guide for guiding the web along its path of advance, the vacuum chamber comprising: a perforated plate extending across the width of the web through which subatmospheric pressure is applied to the web: a central vacuum chamber in communication with the central portion of the perforated plate and having a source of vacuum connected thereto; a side vacuum chamber adjacent to each lateral end of the central vacuum chamber and in communication with lateral portions of the perforated plate, each of the side chambers including a laterally adjustable piston therein for limiting the area of the lateral portion of the perforated plate exposed to the subatmospheric pressure; and a selectively operable valve connecting the central chamber to each of the side chambers for supplying vacuum thereto in a first operating mode and for discontinuing the supply of vacuum thereto in a second operating mode, for controlling the area of the perforated plate through which subatmospheric pressure is applied to the web during changeover from a web one width to a web of another width.

Description

[ Mar. 18, 1975 United States Patent [191 Middleman METHOD AND APPARATUS FOR GUIDING along a path of advance; applying vacuum tension to AND TENSIONlNG A WEB DURING the web substantially across the entire web; applying the vacuum tension to a centermost portion of the web prior to changing the width of the web, the centermost portion being equal to or narrower then the narrowest web to be advanced; and thereafter applymd ED N e owm FR GE mmm 0! Nm AAm Fl. W W mE WM. WA

0 Nmm mmw Cwm ing vacuum tension substantially across the entire [73] Assignee: Kappers Company Inc., Pittsburgh width of the web then being advanced. The preferred apparatus for performing the method is a web guiding [22] Filed: Jan. ll

and tensioning apparatus of the type including a vacuum chamber for applying subatmospheric pressure to App]. No.: 432,454

Related US. Application Data Continuation-impart of Serf No. 236,067, March 20, 1972, Pat. No. 3,788,5l5.

a smooth side of the web for tensioning the web and a guide for guiding the web along its path of advance. the vacuum chamber comprising: a perforated plate extending across the width of the web through which subatmospheric pressure is applied to the web: a central vacuum chamber in communication with the central portion of the perforated plate and having a source of vacuum connected thereto; a side vacuum chamber adjacent to each lateral end of the central vacuum chamber and in communication with lateral portions of the perforated plate, each of the side 5 2M9 95 05 77 7 62 2 24 4 22 2 QhM /mi m mm 22 m 9 1 .l H. I 5 0 n 61 H m mm u 2 H m h Uc U r. U a H U In C U M 5 ma U IF 1 ll 2 oo 5 55 .i ii

S T I N I EH T mm MA mm D m S SE c m mm Ad e .15 "T 8 SSE D 3 99 NHH u m 99 53 5 007. 37 AA Ill 33 Primary Examiner-Richard A. Schacher supplying vacuum thereto in a first operating mode Attorney, Agent, or Firm-Oscar B, Brumback; Boyce and for discontinuing the supply Of vacuum thereto in C. Dent; Olin E. Williams a second operating mode, for controlling the area of the perforated plate through which subatmospheric [57] ABSTRACT pressure is applied to the web during changeover from A method of applying vacuum tension to a web during a web one width to a Web of another w'dth changeover from a web of one width to a web of an- 8 Claims, 7 Drawing Figures other width comprising the steps of advancing the web HJEHTED 1 81575 sum 1 ur 4 haw E m GI IIJMN mmw Wm. NU; WK Dun Mm METHOD AND APPARATUS FOR GUIDING AND TENSIONING A WEB DURING CHANGEOVER FROM A WEB OF ONE WlDTI-I TO A WEB OF ANOTHER WIDTI-I CROSS REFERENCES TO RELATED APPLICATIONS This invention is a continuation-in-part of application Ser. No. 236,067 filed Mar. 20, I972 by David Middleman, and now US. Pat. No. 3,788,5l5, for Method and Apparatus for Guiding and Tensioning a Web assigned to the assignee the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to advancing material of indeterminate length with means to retard material movement and more particularly to a vacuum chamber for guiding and tensioning a web during the changeover from a web of one width to a web of another width.

2. Description of the Prior Art The problems associated with guiding and tensioning single face corrugated paperboard over a web tensioning device located between the delivery end ofa singlefacer and the input end of a double-facer for guiding and tensioning the single-face web prior to entering the double-facer were discussed in the aforementioned copending application and these problems have been mostly overcome by the use of the apparatus and method claimed in such application. However, the earlier application used a single vacuum chamber and the volume of the chamber was increased or decreased by the use of laterally moving pistons within the chamber in order to accommodate different widths of web material. Although this arrangement has many advantages such as, for example. it provides for uniform tensioning across the entire width of the web, it prevents flute crush, and it reduces the noise ordinarily developed by passing the flutes over a stationary object, it does have a distinct disadvantage.

When a web of different width than the web being advanced is to be run in the vacuum chamber of the copending application. the web tensioning device has to be shutdown, the pistons within the vacuum chamber have to be moved to a position where the distance between the pistons is substantially the same as the width of the new web. the web has to be positioned beneath the perforated plate of the vacuum chamber, and the vacuum restored to the vacuum chamber. This proce' dure for accommodating a different width web requires a substantial amount of downtime and thus there is a loss of production time.

The reason for shutting down the apparatus for a web width change is that the pistons have to be moved to their new location. When a web width change is from a wide width to a narrower width the narrow web has to pass beneath the perforated plate before the pistons can be moved. otherwise the web guides that are attached to the pistons will crush the wider width web being run. Thus, when the narrow width web passes beneath the perforated plate vacuum is immediately lost around the ends of the web and therefore tension on the web is also lost. The pistons cannot be moved inward to the new position fast enough to maintain vacuum. Also when going from a narrow width web to a wider width web, the pistons have to be moved apart before the new web passes beneath the perforated plate so that the guides do not interfere with the new wider web. When this is done, vacuum is lost around the ends of the web being run and thus tension is again lost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for guiding and tensioning an advancing web to overcome the aforementioned disadvantages and others and particularly for guiding and tensioning a web during changeover from a web ofone width to a web of another width without having to shutdown the apparatus. This invention also includes suitable apparatus for continuing to supply tension to an advancing web when a web of a different width is passing beneath the perforated plate on a vacuum chamber.

This is generally accomplished by the method of applying vacuum tension to the web during changeover from a web of one width to a web of another width comprising the steps of advancing the web along a path of advance, applying vacuum tension to the web substantially across its entire width, and applying the vacuum tension to a centermost portion of the web prior to changing the width of the web, the centermost portion being equal to or narrower then the narrowest web to be advanced, and thereafter applying vacuum tensioning substantially across the entire width of the web then being advanced.

The preferred apparatus for performing the method includes a vacuum chamber means for a web guiding and tensioning apparatus of the type including vacuum means for applying subatmospheric pressure to a smooth side of the web for tensioning the web and guide means for guiding the web along its path of advance, the vacuum chamber means comprising a perforated plate extending across the width of the web through which subatmospheric pressure is applied to the web; a central vacuum chamber in communication with a central portion of the perforated plate having a source of vacuum connected thereto; a side vacuum chamber adjacent to each lateral end of the central vacuum chamber and in communication with lateral portions of the perforated plate, each of the side chambers including a laterally adjustable piston means therein for limiting the area of said lateral portion of said perforated plate exposed to said subatmospheric pressure; and selectively operable valve means connecting said central chamber to each of the side chambers for supplying vacuum thereto in a first operating mode and for discontinuing the supply of vacuum thereto in a second operating mode, for controlling the area of the perforated plate to which subatmospheric pressure is applied to the web during changeover from a web of one width to a web of another width.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purposes of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts are marked alike. FIG. I is a schematic side view of a single-facer and a double-facer showing a moving single-face webs path of advance from the single-facer, through the guiding and tensioning apparatus of the present invention, and into the double-facer;

FIG. 2 is a perspective view of the web guiding and tensioning apparatus of the present invention looking upward and to the right;

FIG. 3 is a front elevation view of the apparatus of FIG. 2 showing the valve means of the present invention;

FIG. 4 is a side elevation view of the apparatus of FIG. 2 showing a web of material being guided and tensioned;

FIG, 5 is a top plan view of the vacuum chamber of FIG. 2 with the top and bottom plates removed showing an alternate embodiment of the valve means;

FIG. 6 is a front elevation view in cross section taken along line VI-VI of FIG. 3 showing the internal structure of the valve means; and

FIG. 7 is a side elevation view in cross-section taken along line VII-VII of FIG. 5 showing the openings in the lateral ends of the central vacuum chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is shown in FIG. I as it is applied to a corrugated paperboard making machine having a conventional single-facer noted generally by number II wherein a web to be corrugated is first fed over a pre-steamer 22 and then between

corrugating rollers

24 and 26. A facing sheet 28 passes partially around a pressure roll 30 where it is pressed into contact with the peaks of the corrugations in web 20, to which adhesive has been applied to the peaks in a known manner (not shown). Since single-facer 11 may be of known construction and mode of operation, it will not be described; however, it should be understood that web I2 of single-faced corrugated paper travels upwardly from a single-facer 1] to pass between sets of

feed belts

32 and 34 which deliver the web progres sively onto the entrance end of an overhead guide bridge indicated generally at 36. This overhead bridge 36 extends horizontally toward the double-facing section 51 ofthe machine later to be described, and is provided with an appropriate number of traveling belts 38 to feed the single-faced corrugated web 12 progressively right to left as the parts appear in FIG. 1, bridge 36 being shown with flooring 40 supporting web 12 beyond the travel of belts 38.

It has long been customary in operation to maintain on bridge 36 an excess length of web 12 so that web 12 travels along bridge 36 largely in the form of more or less loose folds or loops 42 which do not lie flat against belts 38. Since the above parts of the machine may be assumed to be of known form they are not described in greater detail herein.

At the delivery end of bridge 36 is located the web guiding and tensioning apparatus of the present invention generally denoted by numeral I0. Apparatus I0 is used for guiding web 12 into alignment with a second facing sheet 48 so that a minimum of edge cutting will later be necessary and for applying tension or a dragging force to smooth surface 16 of web 12 between vacuum chamber means 200 and the entrance to the double-facer SI. The amount of tension needed will vary depending on several factors such as the amount of wrap around roll 44 to apply the proper amount of heat to web 12, the web weight. and the like. A preferred construction of apparatus is later described in detail. From apparatus 10, web 12 is shown as passing partially around the preheater roller 44 used in connection with double-facing section 51 of the machine. Web 12 is then fed past an appropriate and conventional adhesive applying mechanism 46 where adhesive is applied to the peaks of the corrugations of web I2. The second facing sheet 48 is shown as being fed partially around a preheater roller 50 to the entrance end 52 of doublefacer section 51 of the machine where the second facing sheet 48 is pressed into contact with the adhesive coated peaks of the corrugations of web 12. Since the above described parts may be assumed to be of known construction, they are not further described in greated detail.

When it is desired to run a different width of web 12 through the single-facer II, it is customary in the corrugating industry to cut

webs

20 and 28 and splice a different width of web to

webs

20 and 28 and then continue operation through single-facer ll, apparatus 10 and through the doublefacer 51.

As previously mentioned at the delivery end of bridge 36 is located the web guiding and tensioning apparatus 10 whose purpose is to guide and tension web 12 as it leaves bridge 36 and enters double-facer Sl. Conventional web guiding and tensioning mechanisms and the one shown in the forementioned co-pending application have some distinct disadvantages, as previously mentioned, especially when a web width change is passing the guiding and tensioning apparatus 10 and it is an object of the present invention to provide a novel means for overcoming the aforementioned disadvantages.

Referring to FIGS. 2 and 3, this invention generally comprises a vacuum chamber means generally noted by numeral 200 for web guiding and tensioning apparatus 10 of the type including vacuum means for ap plying subatmospheric pressure to a smooth side of web 12 for tensioning web I2 and a guide means 98 for guiding web 12 along its path of advance. Vacuum chamber means 200 comprises a perforated plate generally noted as numeral 68 extending the width of web 12; a central vacuum chamber 202 is in communication with a central portion of perforated plate 68 and has a source of vacuum I00 connected thereto; a

side vacuum chamber

204 and 206 adjacent to each lateral end 2I2 of central vacuum chamber 202 is in communication with the lateral portions of perforated plate 68, each of the

side chambers

204 and 206 include a laterally adjustable piston means, generally noted as nu meral 74, therein for limiting the area of the lateral portion of perforated plate 68 exposed to subatmospheric pressure; and a selectively operable valve means, generally noted as numeral 208, connecting central chamher 202 to each

side chamber

204 and 206 for supplying vacuum thereto in a first operating mode and for discontinuing the supply of vacuum thereto in a second operating mode, for controlling the area of perforated plate 68 through which subatmospheric pressure is applied to web 12 during changeover from a web I2 of one width to a web 210 of another width.

The preferred method for applying vacuum tension to a web 12 during changeover from a web 12 of one width to a web 210 of another width generally comprises the steps of: advancing web I2 along a path of advance; applying vacuum tension to web 12 substantially across its entire width; applying vacuum tension to a centermost portion of web 12 prior to changing the width of web 12, the centermost portion being equal to or narrower than the narrowest web to be advanced; and thereafter applying vacuum tension substantially across the entire width of the web then being advanced.

As shown in FIGS. 2-7, for the purpose of clarity, the long dimensions of the guiding and tensioning apparatus across the width of web I2 will be considered its width and the short dimensions along the path of advance of web 12 will be considered its length. A vacuum chamber means 200 (FIGS. 2, 3, and 4) spans the width of bridge 36 at its delivery end. The vacuum chamber means 200 is generally rectangular in shape bounded on the front and back by two spaced parallel supports 56 which span the width of bridge 36 and provide the necessary support and strength for the rest of the parts that make up vacuum chamber means 200, which are to be described in detail later. Vacuum chamber means 200 is bounded on the sides by supports 58 which in turn are attached to bridge 36 by supports 60. Supports 56 are attached to supports 58 by any suitable means, for example, a pair of brackets 62 are spaced and attached to each support 58 such as by welding. Supports 56 are placed between each pair of spaced brackets 62 and secured thereto such as by bolting the flanges 64 of supports 56 to brackets 62. The vacuum chamber means 200 is covered on the top by a cover 66 which spans the width between the two upper brackets 62 and spans the space between the two supports 56 to include flanges 64 so that top 66 may be secured to flanges 64 by any suitable means, such as by screws (not shown]. The bottom of vacuum chamber means 200 is covered by a perforated plate 68 (see FIG. 2) which spans the width between the two lower brackets 62 and spans the space between the two supports 56 to include flanges 64 so that the perforated plate 68 may be secured to flanges 64 by any suitable means such as by screws (not shown). It is to be understood that the aforementioned construction of vacuum chamber means 200 is preferred although other methods of construction may be used, for example, (not shown) the top cover may be rounded to form the shape of a half cylinder whose edges attach directly to the bottom perforated plate thereby eliminating the front and rear supports.

The preferred construction of the internal parts of vacuum chamber means 200 is shown in FIGS. 2 and 5. When referring to FIG. 5 it is to be understood that the internal structure of vacuum chamber means 200 is the preferred construction; however, the valve means depicted in the central chamber 202 is an alternate em bodiment and the preferred valve means 208 is shown in FIGS. 3, 4, and 6.

In the copending application a pair of laterally spaced restraining plates, designated by numeral 70 in the copending application, were secured to supports 56 at substantially the midpoint of vacuum chamber means 200, and were so constructed that there was a space between the tops of plates 70 and top cover 66. In the improvement the laterally spaced restraining plates, now designated by the numeral 212, are secured to supports 56, perforated plate 68, and to top cover 66 forming a substantially air-tight barrier between central vacuum chamber 202 and

side chambers

204 and 206 thus defining three separate vacuum chambers. that is, central vacuum chamber 202 and the two laterally adjacent

side vacuum chambers

204 and 206. The restraining plates 212 are laterally spaced a distance equal to or narrower than the narrowest width web of material being run. thus insuring that the narrowest width web will always be in contact with the central portion of perforated plate 68 which is in communication with central vacuum chamber 202. A pair oflaterally spaced stop plates 72 are secured to supports 56 at each end of

side vacuum chambers

204 and 206. Located between each restraining plate 212 and stop plate 72 is a piston 74. Piston 74 consists of a rectangular plate 76 whose circumference around the outside periphery is less than the circumference around the inside periphery of

side vacuum chambers

204 and 206. Around the outside periphery of plate 76 is attached a flexible seal 78, such as rubber, whose outer periphery is in contact with the inner periphery of

side vacuum chambers

204 and 206, that is to say, seal 78 on each plate 76 is in contact with cover 66, front and rear supports 56, and the bottom perforated plate 68 to form a slidable but substantially air-tight connection. Attached to the outboard surface of each rectangular plate 76 is a rectangular block 80 which serves as additional support for piston 74. A hollow tube 82 is placed through each rectangular plate 2I2; thus the ends of tube 82 will extend beyond the outboard surface of each plate 2I2. It should be understood that the space between tube 82 and plates 212 should be properly sealed with gasket material or the like in order to maintain an air-tight barrier between central vacuum chamber 202 and

side vacuum chambers

204 and 206. A control shaft 84 extends through substantially the mid portions of stops 72, blocks 80, plates 76, and through hollow tube 82. Control shaft 84 is supported for rotation at one end by conventional bearings (not shown) which are mounted in one of the end supports 58; the other end of shaft 84 extends through and beyond similar bearings (not shown) mounted in the other support 58, and is attached to a mechanism capable of rotating shaft 84, such as a control motor 86 as shown in FIGS. 2, 3, and 5. Control motor 86 is supported by attaching it to a platform 88 which is in turn attached to end support 58. Control shaft 84 has left hand male screw threads on substantially one-half of its length and right hand male threads on the other half of its length. Each piston 74 has either right or left hand female threads engageable with the corresponding male threads of shaft 84; therefore, when shaft 84 is rotated, each piston 74 will move simultaneously toward the central vacuum chamber 202 or away from the central vacuum chamber 202 depending on which way shaft 84 is being rotated. Movement of pistons 74 toward or away from central vacuum chamber 202 decreases or increases the volume of the space inside

side vacuum chambers

204 and 206 between each piston 74 and plates 212, thereby limiting the application of subatmospheric pressure to web 12 through perforations 67 in plate 68 located between pistons 74 and plates 212.

Each piston 74 has a support bar 90 on each side of control shaft 84 extending through each piston 74. Each bar 90 is supported at one end by restraining plates 212 and at the other end by stop plates 72. It should be understood that the space between support bars 90 and plates 212 should be properly sealed with gasket material or the like in order to maintain an airtight barrier between central vacuum chamber 202 and

side vacuum chambers

204 and 206. These support bars 90 are provided as guides and supports for pistons 74 as pistons 74 move along their respective paths when control shaft 84 is rotated. A flexible dust cover 83 preferably surrounds control shaft 84 extending from each piston 74 to each restraining plate 212 for protecting the threads on control shaft 84 from dust contamination when subatmospheric pressure is applied to

side vacuum chambers

204 and 206.

Referring now to FIG. 2, perforated plate 68 is preferably flat and includes a central slot 92 extending along the width of perforated plate 68 and at substantially the center of its length. Slot 92 is preferably formed by spacing two similar plates 68a and 68b a short distance apart rather than by cutting a slot 92 in a single plate 68. Attached to surfaces 93 of block 80, which is adjacent to perforated plate 68, and at substantially the center of its length, are support plates 94 which extend laterally at a right angle from the outboard surface of each plate 76 to a point beyond the width of blocks 80. Attached to the surface of support plate 94 adjacent perforated plate 68 are struts 96 which extend through slot 92 and to the exterior of perforated plate 68. Attached to the inside surface of struts 96 at a point exterior of perforated plate 68 are guide plates 98. Guide plates 98 extend at right angles from struts 96 back towards the center of vacuum chamber means 200 as shown in H68. 2 and 5. The function of guide plates 98 will be explained later.

Referring now to FIGS. 2, 3, and 4 in order for the above described vacuum chamber means 200 to guide and tension advancing web 12, subatmospheric pressure must be applied to central vacuum chamber 202. To apply vacuum to central vacuum chamber 202 a motorized suction device 100 is utilized. The preferred suction device 100, and the one illustrated, is a centrifugal blower, but it should be understood that any number of different types of suction devices may be used for applying suction to the interior of central chamber 202. Suction device 100 is supported by two parallel support beams 102 which span the width between bridge supports 60 and are attached thereto. A base 104 spans the two beams 102 and is attached thereto. The suction device 100, which includes a power motor 106 for creating the suction, is attached to base 104. A flexible hose 108 (or rigid pipe if desired) is attached at one end to the input nozzle 101 of suction device 100 and the other end of flexible hose 108 is attached to an opening 110 in one ofthe supports 56 which leads to central vacuum chamber 202. Opening 110 is prefer ably located at substantially the midportion of support 56 to insure even distribution of vacuum in central vacuum chamber 202. Flexible hose 108 is routed where it will not interfere with tensioning and guiding web 12. For example, hose 108 may be secured along support 56 and then along support 58 by hose clamps 112. Suction device 100 also contains an exhaust nozzle 114 which is preferably connected to a conventional muffler and exhaust system 103 by flexible hose 105 for reducing the noise generated by suction device 100.

Referring now to FIGS. 2, 3, and 4, a pair of rotatable roller 118, preferably bearing mounted in the conven tional manner. spans the width between end supports 58, one of which is attached thereto slightly below and at the input end and the other at the output side of vacuum chamber means 200. The rotatable roller 118 may be motor driven, not shown, or free-wheeling as illustrated. The function of the rollers will be described in detail later.

In accordance with this invention, as best illustrated in FIG. 5, vacuum is continuously applied to central chamber 202. When the width of the web is greater than the width of the central chamber, the pistons are moved in the

side chambers

204 and 206 to about the width of the web. Vacuum is then directed to the side chambers so that the total width of the web is subjected to vacuum through perforated plate 68. When a narrower width web, which has been spliced to the trailing end of the wider web, approaches the chamber means 200, vacuum to the side chambers is discontinued. Thus central chamber 202 applies vacuum to the central portion of the wider web and then to the narrower web so it presses beneath perforated plate 68. After the pistons 74 are reposited to accommodate the narrower web, vacuum is again directed to the

side chambers

204 and 206 to apply vacuum to the total width of the narrower web then being run. In this manner, it is unnecessary to completely discontinue the vacuum since no vacuum pressure is lost in the side chambers when the narrower web passes beneath the perforated plate before the pistons 74 are repositioned. Similarly, the same result is achieved when a narrow web is changed to a wider web.

The supply of vacuum from central member 202 to side

Chambers

204 and 206 is controlled by a valve means 208. Referring to FIGS. 2 and 6, valve means 208 comprises an opening or port 214 which extends through top cover 66 and into central vacuum chamber 202. A second opening or port 216 extends through top cover 66 into side vacuum chamber 204 and a third opening or port 218 extends through top cover 66 into side vacuum chamber 206.

Ports

212, 214, and 216 are laterally aligned along the width of top 66 of vacuum chamber means 200.

Referring now to FIGS. 3, 4, and 6, a conduit 220

interconnects ports

214, 216, and 218. The ends 222 and 224 of conduit 220 is secured to top cover 66 over

ports

216 and 218 such as by bolting or welding to form an air-tight connection. The central portion of conduit 220 includes a leg 226 which is secured to top cover 66 over port 214 in the same manner as ends 222 and 224. Leg 226 is made of greater diameter than port 214. A washer 228, made of rubber or other resilient material, is secured to top cover 66 around port 214 as shown in FIG. 6.

An actuator means generally noted by numeral 230, comprises a support 232 which is secured to the top of conduit 220 and in alignment with port 214. A conventional pneumatic cylinder 234 is secured to support 232 and in alignment with port 214. Preferably, pneumatic cylinder 234 comprises a housing 236 whose one end is secured to support 232. A piston 238 inside housing 236 is in sliding engagement with the inner surface of housing 236. A piston rod 240 is connected to piston 238 and extends through housing 236, support 232, conduit 220, and into leg 226. Connected to end 242 of piston rod 240 is a rigid plate 244 whose diam eter is greater than the diameter of port 214 but less than the diameter of leg 226. A spring 246 is secured to the other side of piston 238 and extends to the top of housing 236 for pushing piston 238 downward, to be explained in connection with the operation ofthe apparatus. An air inlet pipe 248 is connected at one end to housing 236 between piston 234 and the bottom of housing 236 which is connected to support 232 and the other end of pipe 248 is connected to a manually operable valve control panel 250 (FIG. 3). Control panel 250 is connected to an air supply, not shown, by pipe 252 and also contains an air exhaust pipe 254 which is connected to the outside atmosphere or other suitable exhaust systems, not shown. Although control panel 250 is shown in close proximity to valve means 208, it should be understood that it can be remotely positioned where it is convenient for the machine operator to operate the controls.

Although the preferred embodiment has been described for actuator means 230, it should be understood that other actuator means may also be used. For example, instead of using spring 246 between piston 238 and housing 236, another air inlet pipe, not shown, may be connected to control panel 250 and housing 236 between piston 238 and top of housing 236. Air pressure can then be used instead of spring pressure to push piston 238 downward. Also, an electrically operable solenoid and piston rod arrangement, not shown, can be used instead of the preferred pneumatic cylinder and piston 234. Further, a hydraulic cylinder and piston arrangement, not shown, can be used instead of a pneumatic cylinder and piston.

If desired, a pair of actuator means, not shown, can be used instead of a single actuator means. With this arrangement an actuator means can be positioned at each

end

222 and 224 of conduit 220 in the same general manner as the preferred single actuator is positioned at leg 226, and thus the vacuum in each

side chamber

204 and 206 can be individually controlled from control panel 250.

FIG. 5 illustrates an alternate embodiment for a valve means to control vacuum supplied to

side vacuum chambers

204 and 206. In this arrangement an opening or port 256 extends through each lateral restraining plate 212 forming a passageway between central vacuum chamber 202 and each

side vacuum chamber

204 and 206. A pneumatic cylinder and dual piston 258 is laterally aligned with each port 256 inside central vacuum chamber 202. Cylinder 258 has a pair of pistons (not shown) with a piston rod 262 extending laterally from each piston and in alignment with each port 256. A rigid plate 264 is secured to each end of each piston rod 262. Rigid plates 264 have a diameter greater than ports 256 so that plates 264 will cover each port 256. If desired, a washer, not shown, similar to washer 228 in the preferred embodiment may be secured around each port 256 on the inside surface of each plate 212 in order to insure an air-tight seal. Connected between each piston within cylinder 258 is a spring, now shown, for exerting lateral pressure on each piston. A pair of air pipes 266 are connected to cylinder 258 between each end of cylinder 258 and each piston. The other ends of pipes 266 are connected to a valve control panel 268. If desired control panel 268 may be of the same type and configuration as that used in the preferred embodiment.

OPERATION In operation, web 12 moves from the single-facing operation 11 to overhead bridge 36 where belts 38 move web 12, which is folded into loops 42, toward the delivery end of bridge 36. At the delivery end of bridge 36 is the guiding and tensioning device of the present invention. The vacuum chamber means 200 may be spaced just slightly above bridge 36 with the bottom of perforated plate 68 in contact with the top smooth surface 16 of web 12 and the web advances horizontally along bridge 36 so that web 12 may be guided almost directly horizontally into the apparatus, but the preferred method is to have vacuum chamber means 200 spaced a substantial distance above bridge 36 as shown in FIG. 1 so that loops 42 are pulled upward out of web I2 prior to its entering the apparatus. Vacuum chamber means 200 is supported above bridge 36 by end supports 58, as previously described.

Web 12 is fed over input roller H8 and under perforated plate 68 so that the smooth surface l6 of web 12 is in contact with perforated plate 68 and the fluted surface of web 12 is in contact with input roller "8. Web 12 is then fed over output roller 118, around preheater roller 44, and into doubIe-facer 51. Motor 86 is energized by suitable conventional controls (not shown) thereby rotating control shaft 84 in the desired direction. Since pistons 74 are engaged with control shaft 84, rotation of control shaft 84 will simultaneously move pistons 74 toward plates 212, thus toward the edges of web 12. As illustrated in FIGS. 2 and 5, strut 96 is connected to piston 74 by support plate 94, and strut 96 extends through slot 92 to the exterior of perforated plate 68. Guide plates 98 in turn are connected to struts 96 exterior of perforated plate 68. Therefore, when pistons 74 advance or retract along their path of advance, guide plates 98 will also advance and retract. The machine operator, by activating motor 86, can move guide plates 98 along their path of advance until they are in contact with the edges of web l2, at which time motor 86 is de-energized by the operator, which stops any further advance of guide plates 98. The guide plates 98 are then in a position to guide web 12 along its path of advance by being in contact with the edges of the web.

As guide plates 98 are positioned, pistons 74 are also positioned since both are interconnected by motor 86 and control shaft 84. As pistons 74 advance, flexible seals 78 contact the inner periphery of

side vacuum chambers

204 and 206, thereby defining the active volume in each

side vacuum chamber

204 and 206, and central vacuum chamber 202 subjected to subatmo spheric pressure. When guide plates 98 are in contact with the edges of web 12, the separation distance between each piston 74 will be substantially the same as the width of web 12. Thus, no suction is lost through the perforations lying outside the width of web 12.

For illustration purposes it will be assumed that the width of the initial web 12 being run is substantially wider than central vacuum chamber 202. It should be understood however, that any width web may initially be run as long as its width is equal to or wider than the separation distance between fixed plates 212.

When pistons 74 are in position and guides 98 are in contact with the edges of web 12, the machine operator opens an air valve in control panel 250 which allows air under pressure to flow through control panel 250, pipe 248, and into air cavity 251 in pneumatic cylinder 234. Air pressure exerted on piston 238 lifts piston 238 upward compressing spring 246 and in turn lifts piston rod 240 and rigid plate 244 off seat 228. The operator then closes a valve in control panel 250 to maintain the air pressure in pneumatic cylinder 234 in order that rigid plate 244 remains in a position spaced above seat 228. With rigid plate 244 not contacting seat 228, a passageway exists from central vacuum chamber 202, through port 214, conduit 220,

ports

216 and 218, and into

side vacuum chambers

204 and 206.

Activation of suction device 100 causes subatmospheric pressure to be applied in central vacuum chamber 202 and through port 214, conduit 220,

ports

216 and 218 and into

side vacuum chambers

204 and 206 thus causing a vacuum to be created in the space between pistons 74. The smooth side 16 of web 12 is thereby lifted and pressed against perforated plate 68 thereby causing tension or a dragging force to be applied to the smooth surface 16 of web 12 between vacuum chamber means 200 and the entrance to the double-facer 51. The amount of tension needed will vary depending on several factors such as the amount of wrap around roll 44 to apply the proper amount of heat to web 12, the web weight, and the like. A conventional damper valve 116 on the side of central chamber 202 can be adjusted to regulate the magnitude of the tension applied to web 12 by controlling the amount of atmosphere that is allowed to return to central vacuum chamber 202.

Activation of single-facer l1 and doublelfacer 51 causes web 12 to move along its path of advance. As the fluted surface of web 12 moves over input roller 118. input roller 118 will begin to rotate at the same speed as advancing web 12 due to the flutes being pulled over input roller 118. As the flutes are not dragged over a stationary object, but are allowed to flow over a free-wheeling rotatable roller, vary little noise is created at this point. As web 12 passes under perforated plate 68, tension is applied to the smooth surface 16 of web 12. Since the smooth surface 16 of web 12 is sliding across perforated plate 68 rather than the fluted surface, the noise level at this point is greatly reduced because the individual flutes are not being dragged over perforated plate 68. Also, since the tension is applied to smooth surface 16 of web 12, and smooth surface 16 is in contact with perforated plate 68 rather than the fluted surface, the fluted surface is not subjected to flute crush while web 12 is being tensioned nor is any force present tending to pull the corrugated medium away from the smooth liner 16. Web 12 then passes over output roller 118 causing it to rorate which again creats little or no noise. The passage of web 12 over input and output rollers 118 is helpful for guiding and supporting web 12 along a straight flat path under flat perforated plate 68 thereby reducing the possibility of web 12 becoming disengaged from perforated plate 68 by tension in the portion of web 12 between roller 118 and wrap roll 44 while tension is being applied to web 12. Rollers 118 also keep web 12 in position in the event suction pressure is temporarily iost.

When it is desired to run a web of different width than web 12 being run, the machine operator splices new width web 210 (FIG. 2) to web 12 as previously described. For illustration purposes, the operation will first be described for changing over to a web of narrower width than the web being run as shown in FIG. 2 and then the operation will be described for changing over to a web of wider width (not shown) than the web being run.

As the splice between wide width web 12 and narrow width web 210 approaches vacuum chamber means 200, the machine operator opens a valve in control panel 250 which allows the air in cavity 251 of pneumatic cylinder 234 to be released to the outside atmosphere through pipe 254. When the air pressure being exerted on piston 238 has been released. spring 246 expands pushing piston 238, piston rod 240, and rigid plate 244 downward until rigid plate 244 is in contact with seat 228. In this position, rigid plate 244 covers port 214 and closes conduit 220 from central vacuum chamber 202. With port 214 closed by plate 244, vacuum is discontinued from conduit 220 and thus from

side vacuum chambers

204 and 206, but since suction device is connected to central vacuum chamber 202, vacuum is still being applied to central vacuum chamber 202, thus continuing to apply tension to the central portion of web 12 through the central portion of perforated plate 68.

When the trailing edge of web 12 passes beneath perforated plate 68, the narrower width web 210 also passes beneath perforated plate 68 and since web 210 is as wide as or wider than the width of central vacuum chamber 202, vacuum tension is applied to the center portion of web 210. Once web 12 is beyond vacuum chamber means 200, guides 98 are no longer in contact with the edges of web 12 and since web 12 is wider than web 210, guides 98 are not in contact with the edges of web 210. The machine operator then activates motor 86 which in turn rotates screw 84 in the proper direc tion to propel pistons 74 and consequently guides 98 toward central vacuum chamber 202. When the guides 98 contact moving web 210 the machine operator deactivates motor 86 thus stopping pistons 74 and guides 98 along the edges of web 210. The machine operator then activates the air valve in control panel 250 which allows air under pressure to enter cavity 251 in pneumatic cylinder 234 pushing piston 238 upward and compressing spring 246. When piston 238 is pushed upward, rigid plate 244 is lifted off seat 228 by piston rod 240, thereby i e-establishing a passageway from central vacuum chamber 202 to

side vacuum chambers

204 and 206. The vacuum in central vacuum chamber 202 is thus reapplied to

side vacuum chambers

204 and 206 through the passageway created by port 214, conduit 220, and

ports

216 and 218. When the vacuum is reestablished inside

vacuum chambers

204 and 206, tension will be applied across the entire width of web 210 being advanced.

When a web width changeover is desired from a nar row width web to a wider web, the machine operator watches for the splice approaching vacuum chamber means 200 and when desired he opens a valve in control panel 250 which allows the air in cavity 251 of pneumatic cylinder 234 to be released to the outside atmosphere or other suitable exhaust systems by exhaust pipe 254. With no air pressure acting on piston 238, spring 246, which was in compression, forces piston 238 downward until rigid plate 244 contacts seat 228. When rigid plate 244 covers port 214, vacuum is discontinued from

side vacuum chambers

204 and 206. The vacuum still being applied in central vacuum chamber 202 continues to tension the narrow web as it advances. Once vacuum is discontinued to

side vacuum chambers

204 and 206, the machine operator activates motor 86 which rotates shaft 84 in the correct direction to move pistons 74 and guides 98 away from central vacuum chamber 202 before the wider web reaches the apparatus. When guides 98 are spaced at distance sub stantially equal to the width of the new wider web. the machine operator deactivates motor 86 which stops pistons 74.

With pistons 74 and guides 98 in the proper position, the new wider web passes between guides 98 and beneath perforated plate 68. When the new web passes over output roller 118, the machine operator opens an air valve in control panel 250 causing air under pressure to enter cavity 251 of pneumatic cylinder 234 which pushes piston 238 upward compressing spring 246 and lifting rigid plate 244 off of seat 228 thus reestablishing the passageway between central vacuum chamber 202 and

side vacuum chambers

204 and 206. When the passageway has been re-established, vacuum from central chamber 202 is reapplied to

side vacuum chambers

204 and 206 through the passageway thereby causing tension to be supplied across the entire width of the new web being run.

When using the alternate pneumatic cylinder 258, the sequence of events is exactly the same as previously described for the preferred embodiment. In this arrangement, however, air under pressure is supplied by both air pressure lines 266 to the cavity between each piston and each end of pneumatic cylinder 258 by the operator operating the valve controls in control panel 268 thus moving each piston toward the center of pneumatic cylinder 258. This action draws each rigid plate 264 away from each opening 256 in each lateral plate 212 thus providing a passageway between central vacuum chamber 202 and

side vacuum chambers

204 and 206, and thereby allowing vacuum in central vacuum chamber 202 to be applied to each

side vacuum chamber

204 and 206. When it is desired to discontinue vacuum to

side chambers

204 and 206, the machine operator opens the valves in control panel 268 releasing the air to a suitable exhaust system. This causes the spring in pneumatic cylinder 258 to propel each of the pistons outwardly until each rigid plate 264 covers each opening 256 in each lateral plate 212 thus closing the opening in each lateral plate 212 and preventing vacuum from being applied to

side chambers

204 and 206.

It should be pointed out that a conventional overload relay (not shown) may be connected to motor 86 so that in the event pistons 74 are advanced until they contact restraining plates 212, the overload relay will activate and cause motor 86 to shutdown, thereby stopping the rotation of shaft 84 and advancing pistons 74. Also, a conventional limit switch 120 may be positioned on the inboard surface of stop 72 to deactivate motor 86 should pistons 74 be separated to their maximum limit thereby stopping the rotation of shaft 84 and retracting pistons 74. These features prevent the possibility of binding the cooperating threads on the pistons 74 and shaft 84.

The foregoing has presented a novel method and apparatus for guiding and tensioning an advancing web along its path of advance by applying a controlled tension to the smooth surface of the web. in addition, tension is applied only to a centermost portion of the web to allow time for adjustment of the tensioning area when a web of one width is being changed over to a web ofanother width, thus allowing the web to be continually advanced even during the web width changeover.

The apparatus for guiding and tensioning the web has been illustrated as being positioned above the bridge because as the web moves along the bridge, the smooth surface of the web is facing up and in order to apply tension to the web, the webs top smooth surface must contact the bottom perforated plate of the apparatus. Should the single-faced web material be processed so that the smooth surface ofthe web is facing down when the web is moving along the bridge, the apparatus may be inverted so that the perforated plate is facing up and substantially coplanar with the support surface of the bridge. As the web moves along the bridge, the smooth surface of the web can then pass over the perforated plate for applying tension thereto. It should be noted that additional devices may be used, such as blowers or mechanical guides, to straighten the loops prior to the web passing over the perforated plate.

It has also been found that crowning the face of output roller 118 causes the single-face web to remain substantially centered across the width of tensioning and guiding apparatus 10 as it advances beneath perforated plate 68. Thus, there is less tendency of the web to shift laterally and jam against the side guides 98. For example, the output roll 118 is preferably crowned 0.125 inches; that is, the diameter of the center of the roller is 0.125 inches greater than the diameter of its ends. The amount of crown is not critical and may vary in proportion to the length of the roller and its nominal diameter. The output roller 118 is crowned rather than input roller 118 since the web is under tension on the output side of apparatus 10 whereas it is rather slack as it enters the tensioning apparatus. In fact, the input roller 118 can be a fixed arcuate member rather than a roller if desired.

Accordingly, the invention having been described in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

1. Vacuum chamber means for web guiding and tensioning apparatus of the type including vacuum means for applying subatmospheric pressure to the smooth side ofa web for applying tension thereto and including guide means for guiding said web along its path of ad vance, said vacuum chamber means comprising:

a perforated plate extending across the width of said web through which subatmospheric pressure is applied to said web;

a central vacuum chamber in communication with a central portion of said perforated plate and having a source of vacuum connected thereto for applying said subatmospheric pressure to said central portion;

a side vacuum chamber adjacent each lateral end of said central vacuum chamber in communication with lateral portions of said perforated plate for applying subatmospheric pressure from said central chamber to said lateral portions, each of said side chambers including a laterally adjustable piston means therein for limiting the area of said lateral portions of said perforated plate exposed to said subatmospheric pressure; and

selectively operable valve means connecting said central chamber to said side chambers for supplying subatmospheric pressure thereto in a first operating mode and for discontinuing the supply of subatmospheric pressure thereto in a second operating mode,

for controlling the area of said perforated plate through which subatmospheric pressure is applied to said web during changeover from a web of one width to a web of another width.

2. The vacuum chamber means of claim 1 wherein said valve means includes:

a conduit connecting said central chamber to each of said side chambers for supplying subatmospheric pressure thereto; and

an actuator means for discontinuing the supply of subatmospheric pressure through said conduit in said second operating mode.

3. The vacuum chamber means of claim 1 wherein said valve means includes:

an actuator means for closing an opening between said central vacuum chamber and each of said side chambers for discontinuing the supply of subatmospheric pressure to said side chambers through said openings in said second operating mode.

4. The apparatus of claim 1 further including:

a roller for guiding said web out of contact with said perforated plate, said roller being crowned for centering said web along its path of advance.

5. A method of applying tension to an advancing web during changeover from a web of one width to a web of another with comprising the steps of:

advancing said web of one width along a path of advance'.

applying subatmospheric pressure to said web of one width substantially across its entire width to cause tension therein;

applying said subatmospheric pressure to a central portion of said web of one width and discontinuing the application of subatmospheric pressure to adjacent lateral portions thereof prior to changing the width of said web, the width of said centermost portion being substantially equal to or narrower than the narrowest web to be advanced; and thereafter applying subatmospheric pressure substantially across the entire width of said web of another width then being advanced.

6. The method of claim 5 wherein applying subatmo spheric pressure to said web of one width comprises the steps of:

applying subatmospheric pressure to said central portion ofsaid web of one width through a central vacuum chamber means of substantially fixed volume and to said lateral portions of said web of one width through laterally adjacent vacuum chamber means of adjustably variable volume.

7. The method of claim 6 wherein discontinuing the application of subatmospheric pressure to said lateral portions of said web of one width comprises the step of:

disconnecting a source of subatmospheric pressure to said laterally adjacent vacuum chamber means.

8. The method of claim 7 and the additional steps of:

adjusting the volume of said laterally adjacent vacuum chamber means to correspond substantially to the width of said web of another width then being advanced; and thereafter applying subatmospheric pressure to said lateral portions of said web of another width through said laterally adjacent vacuum chamber means.

Claims

1. Vacuum chamber means for web guiding and tensioning apparatus of the type including vacuum means for applying subatmospheric pressure to the smooth side of a web for applying tension thereto and including guide means for guiding said web along its path of advance, said vacuum chamber means comprising: a perforated plate extending across the width of said web through which subatmospheric pressure is applied to said web; a central vacuum chamber in communication with a central portion of said perforated plate and having a source of vacuum connected thereto for applying said subatmospheric pressure to said central portion; a side vacuum chamber adjacent each lateral end of said central vacuum chamber in communication with lateral portions of said perforated plate for applying subatmospheric pressure from said central chamber to said lateral portions, each of said side chambers including a laterally adjustable piston means therein for limiting the area of said lateral portions of said perforated plate exposed to said subatmospheric pressure; and selectively operable valve means connecting said central chamber to said side chambers for supplying subatmospheric pressure thereto in a first operating mode and for discontinuing the supply of subatmospheric pressure thereto in a second operating mode, for controlling the area of said perforated plate through which subatmospheric pressure is applied to said web during changeover from a web of one width to a web of another width.

2. The vacuum chamber means of claim 1 wherein said valve means includes: a conduit connecting said central chamber to each of said side chambers for supplying subatmospheric pressure thereto; and an actuator means for discontinuing the supply of subatmospheric pressure through said conduit in said second operating mode.

3. The vacuum chamber means of claim 1 wherein said valve means includes: an actuator means for closing an opening between said central vacuum chamber and each of said side chambers for discontinuing the supply of subatmospheric pressure to said side chambers through said openings in said second operating mode.

4. The apparatus of claim 1 further including: a roller for guiding said web out of contact with said perforated plate, said roller being crowned for centering said web along its path of advance.

5. A method of applying tension to an advancing web during changeover from a web of one width to a web of another with comprising the steps of: advancing said web of one width along a path of advance; applying subatmospheric pressure to said web of one width substantially across its entire width to cause tension therein; applying said subatmospheric pressure to a central portion of said web of one width and discontinuing the application of subatmospheric pressure to adjacent lateral portions thereof prior to changing the width of said web, the width of said centermost portion being substantially equal to or narrower than the narrowest web to be advanced; and thereafter applying subatmospheric pressure substantially across the entire width of said web of another width then being advanced.

6. The method of claim 5 wherein applying subatmospheric pressure to said web of one width comprises the steps of: applying subatmospheric pressure to said central portion of said web of one width through a central vacuum chamber means of substantially fixed volume and to said lateral portions of said web of one width through laterally adjacent vacuum chamber means of adjustably variable volume.

7. The method of claim 6 wherein discontinuing the applicatiOn of subatmospheric pressure to said lateral portions of said web of one width comprises the step of: disconnecting a source of subatmospheric pressure to said laterally adjacent vacuum chamber means.

8. The method of claim 7 and the additional steps of: adjusting the volume of said laterally adjacent vacuum chamber means to correspond substantially to the width of said web of another width then being advanced; and thereafter applying subatmospheric pressure to said lateral portions of said web of another width through said laterally adjacent vacuum chamber means.