CA1275978C - Air conveyor for plastic film - Google Patents

Abstract

Abstract of the Disclosure An air conveyor for moving heavy guage waste film from film producing equipment to a waste disposal unit wherein the air conveyor reduces the effective width of the film as it is moved to the disposal unit.

Description

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The present invention is directed to an air conveyor for gathering waste film and conveying the film ln web form to a convenient disposal unit such as a scrap g:rinding unitO A prin-cipal function of the air conveyor is to gather the film in man-- 5 ageable form for delivery to the scrap grinder.

In a typical manufacturing operation for fabricating heavy plastic film such as 7 to 15 mil Mylar (a trademark), the plastic is extruded and drawn in web form through the fabricating equipment to windup rolls~ During the course of manufacture, large quantities of scrap are generated which must be disposed of. In start-up operations, substandard film is usually formed as the forming equipment is brought to normal operating condi-tion. In addition, during periods of normal manufacturing opera-tion, the film web may break occasionally causing a massivepileup of waste film on the plant floor.

There are existing air conveyors for disposing of rela-tively thin gauge film which accumulates during a manufacturing mishap. In such air conveyors, the film is moved and conveyed through the action of the conveyor air ~ets. However, stiffer or heavier film material of from 7 to 15 mils cannot be gathered or converged into convenlent form for introductlon into a scrap grinder. Heavy film behaves as does she~t metal, plywoPd, or 25 cardboard in that they fold only in one dimension at a time and are not susceptible to forming compound bends without crinkling or creasing. Because heavy film creases or crinkles, it cannot be handled by an air conveyor of the type used for disposing of thin gauge film.
: At present therefore, thick scrap film is handled manu-~ ally. Substandard waste film generated during startup operations :~ is pulled aside and accumulated until normal film forming machine : operation is achieved. Then the waste film is disposed of manu-ally. Should the film web rupture during machine opsration, the film formlng e~uipment must be shut down while the scrap film is :

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~ 7S~7~3 gathered and remov~d.

The present invention is directed to an air conveyor for removing waste or scrap heavy fllm material such as Mylar between approximately 7 to 1~ mils. An air conveyor according to the present inventlon takes waste f~lm in web form and reduces its effective width by a factor of up to 7 to 1 by forming a transverse generally uniform sinusoidal corrugation or pleat in $he film. In this pleated form the waste film may be introduced into any suitabl~ scrap disposal unik such as a scrap grinder or chipper for reprocessing.

In a preferred form, an alr conveyor according to the invention includes an entrance section and a corrugating or pleating for conveying and pleating waste film. The entrance section of the conveyor comprises an air conveyor of known con-struction including a plenum chamber and a deck plats incised with slots arranged to issue ~ets of conveying air in the direc-tion of conveyance. The conveyor is at least as wide as the web of waste film in order to obtain initial control of the film.
; The corrugating or pleating section of the conveyor cooperates with the entrance section to define a continuous conveying path for the film. The conveyor corrugating section comprises con-- fronting n~sted conveyor surfaces which cooperate to impart a transverse generally sinusoidal curvature to the moving web.
That is to say, the web enters the pleating section with its - leading edge belng in a generally straight line confiyuration and leaves with the leading edge in a generally slnusoidal curve. ~s a result of this transition in shape, the waste film web is reduced in width and is in a more convenient form for introduc-tion into a film disposal unit.

The conveyor pleating saction preferably comprises - upper and lower portions with their conveying surfaces being in confronting relatlon to each other and being spaced apart a gap sufficient to acco~modate the travelling web. One of the con-"

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veyor portions has a surface which develops 1nto t~o or more troughs each increasing in depth in the direction of conveyance as the conveyor converges toward its exit end. One or more ridges separate ad~acent troughs so that a transverse cross-sec-tion of the exit end of the pleater is generally sinusoidal inform.

The other portion of the conveyor pleatlng section is similarly formed o~ troughs and ridges to give a generally sinu-soidal transverse curve at the pleater exit end. The upper andlower portions are nested with each ridge of one lying along a trough of the other portion of the pleating section.

The over result then is a conveyor pleater section which receives a generally flat waste film web and reforms the web to have a generally sinusoidal transverse curve so that as the web moves it is reduced in overall width.

It is to be understood that the deck plate surfaces of the trough and rldge portlons of the pleating seckion are incised with slots for issulng conveying air ~ets for moving the film material.

The conveyor may be provided with one or more exlt con-veyor sections for preserving the sinusoldal form of the film asit moves to the waste disposal unit. The exlt conveyor sections serve also to continue converging the pleated film after it leaves the film pleating section. Preferably the exit conveyor has confronting air conveyor sections positioned along opposite sides of the pleated web and in converging relation to each other ~; along the path of conveyance.

After leaving the exi~ conveyor sectlon, the film is ~;~ introduced into a scrap grinder or other disposal unit.

According to one aspect thereof the present invention .: `, , . " ,: . !

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thus provides an air conveyor for conveying plastic film web of predetermined width and indetermlnate length comprising an entrance section having a width at least as wide as the film being conveyPd, said entrance section comprislng a deck plate having slots oriented to issue air ~ets for conveylng the film along the entrance section, a pleater section located downstream of said entrance section, said pleater section comprising air conveyor sections positioned over and under said film web, said over and under sections each having W-shaped deck surfaces in nested confronting relationship to define a gap therebetween hav-ing a generally sinusoidal profile ext~nding transversely of the film, each of said W-shaped deck surfaces having slots therein for issuing conveying air ~ets ln the direction of conveyance, means for supplying air under pressure to both the entrance and pleater sections of the air conveyor whereby the air conveyor reduces the width of the film by imparting a generally slnusoldal shape thereto.

According to another aspect thereof the present inven-tion provides an air conveyor for conveying plastic scrap filmcompr~sing an entrance section at least as wide as the film being conv~yed, said entrance section havlng a perforated deck plate and a plenum chamber cooperating to generate air ~ets for moving the film along the perforated deck, means for supplying pressur-ized air to said plenum chamber, a pleater section comprisiny confronking air conveyor sections having deck plate surfaces defining a generally sinusoidal gap therebetween positioned over and under said film web for conveying and reducing the width of - the film as it is conveyed, the deck plate surfaces being nested W-shaped surfaces, and means for grinding the film.

Thus, the present invention provides a conveyor capable of use in controlling and conveying waste film to a disposal unit~

The present invention also provides an air conveyor as part of a film-forming installation to enable removal of waste film generated during film forming operations.

The present invention again provides an air conveyor for removal of heavy gauge film such as Mylar~

The present invention further provides an air conv~yor which transforms generally flat heavy fllm into a convenient form for disposal by imposing a generally sinusoidal transverse curva-ture to the film as it is conveyed to a disposal unit.
A preferred embodiment of the invention has been chosenfor purposes of illustrating and describing the principles o~ the invPntion and is shown in the accompanying drawing, in which:-Figure 1 is a schematic side elevational view, partlyin section, showing an overall factory layout of an air conveyor for heavy film according to the invention;

Figure 2 is a plan view of the air conveyor portion of Figure 1 with the top pleater unit removed;

Figure 3 is a fragmentary perspective view of an air slot incised into the air conveyor deck plate surface for issuing conveying air ~ets;
~: ' : Figure 4 is a sectional view taken along line 4-4 of Figure 2 showing the incline nf a trough portion of the lower pleater unit of the air conveyor;

Figures 5 through 8 are sectional vlews taken along lines 5-5 through 8-8 of Figure 2, respectlvely, illustrating the surface contour o~ the lower plea~er unit of the air conveyor;

: 35 Figure 9 is a plan view of the deck plate surface o~
the top pleater unit;

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~Z~5~78 Figures 10 through 13 are sectional views taken along lines 10-10 through 13-13 of Figure g to illustrate the surface contour of the top pleater unit deck surface;

Figure 14 is a sectional view taken along line 14-14 of Figure 2 to illustrate the generally sinusoidal shape imparted . ~ .

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_J heavy ~ilm by the air conveyor.
Figures 15 and 16 are perspcctive views of tlle lowexand upper portions respectively o~ t:hc pleatcr section of the air conveyor.
Figure 17 is a section view ~aken alon~ line 17-17 of Fiyure 1 to ~how tlle generally sinusoidal contour assumed by heavy film as it enters the film chipper.
Referring now to the drawing and in particular -to Figure 1, a heavy film air conveyor 10 of the invention is intended primarily for use in a factory for producing heavy film 12 such as Mylar of between 7 and 15 mils ~:n thickness which is formed and drawn over a support roll 14 to a windup roll 16. ~ noted above, large amounts of w~ste film are generated durincJ startup operàtions, and occasionally during a production run when ~he Eilm web ruptures. In practice, air conveyor 10 is posi~ioned below a suitable opening 18 in the factory 100r 20 in order to capture and convey waste film to a film chipper or grinder 22. `~ -~he air conveyor may be oriented horizontally as shown, or if deslred it may be orier,ted vertically or at an incline.
The air conveyor includes an entrance SectlQn 24 preferab1y at leask as wide as the film being conveyed. The entrance sectlon captures the leading edge portion of the film, carries i~ through a pleater section 26, tllrough converging side panels ~8, 30, and into the film chipper 22.
ns the ~ilm is moved it changes shape from a flat sheet to the generally sinusoidal transverse form shown in Figure ~7.
The conveyor entrance sec~ion comprises an air conveyor having a per~orated deck plate 32, a plenum chamber 34 r and and air fan or b]ower 36 for ~upplying pressurized air throu~h a transition duct 38 to the plenum chamber. The plenum chamber is fully enclosed and defined by side ~0, ~ottom .

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92, and end walls ~, and deck pla~e 32. Tllc dccl~ platc de~incs tllc convcy:ing sur~ace o~ tlle conveyor and is perfora~ed with air slots ~G whicll emit jets of conveying air indica~ed by arrows. I~acll air jet l~as a major conveying componen~ along -the surace of the declc plate. The air slots 46 are incised into the deck plate as shown in Figure 3 by cutting the deck plate 32 and depressing the down-stream portion 4B of the deck plate ~o define air ~et slot 46.
~ t the outset it should be understood that the deck plate surfaces of the entrance section 24, the pleater section 26, and the side panels 28, 30 all have surEaces perfoxated with a~ir slots o~ the configuration shown in ~igure 3, Waste film 12 generated durincJ fi.lm forming operal:ions moves through floor open.lng 1~ and i5 cap tured by the entrance sec-tion 24 o~ the air conveyor. ~ccording to the invention, -the film is converged throuyh the pleater section 26 and side panels 28, 30 of the conveyor and is reduced in width for feeding into the film chipper 22.
The pleated section 26 of the air conveyor prefera~ly comprises upper SO and lower 52 portions which cooperate to transform the film from a relatively flat condition in which the leading edge approximates a strai~ht line ~in edge view) to a generally sinusoidal condi~ion in which the film leading edge talces on the wave form sho~in in Figure 17. This change ln form reduccs the film width ~nd facilitates int.roduction of the fi].m into the filn~
chipper 22.
The lower unit 52 of the pleater has a generally "W"-shaped cross-section wit~l ~he "W"-shape developing in depth and convergance in tlle conveyin~.direction in manner illus~ratcd in rigures s-n. Tllat is to say, the ~ower pl~atcr unit 52 includes m~rgin~l ridges 54 following ~75~
th~ allgle o~ convercJoncc o tlle plcated section and a ccntral ridgc 5G convcrging in the direction oE conveyancc. ~acll o tlle mar~inal and central ridges arc coplanar wi~ll the declc p]a~c surface o~ tlle entrance section o~ the convey~r. Tlle marginal and c~ntral ridges are separatcd by intervening trouglls 58 which,also convcrge in the conveying direction. In addition, eacll trough is inclincd in the conveying dir~ction as shown in Fiyure 4.

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~ djacent ridges 54, 56 and trouyhs 58 are soparated by wedge-shaped gusse~s ~0 which become wider in the direction of conveyance ,so as to connect contiguous ridge and trougll surfaces.
The surfaces of ridge, gusset and trough define an activo conveying surface 51 per~orated with air slots,46 for issuing air jets in tlle direction o~ conveyance. If desired the marginal ridges may have air jets oriented to issue air jets in khe di:c~ction eonvergence. The overall effect o~ air jets in the pleater section is to move the film in the conveying direction so that it assumes a "W"-shape or generally sinusoidal transverse shape for convenient entry into the ilm chipper. , - ,~
~ s best shown ln Figures 1 and 9 through 16, the pleater section includes an upper unit 50 having an active air conveyor sur- -face 53 formed wlth ridges 62 and trough 64 arranged to nest with the active surface of the lower pleater unit in fo~mlng a "W" shaped gap 66 (Figure 14) for pleating -the film 12. The upper unit includes a plenum chamber 55 supplied with pressurized air in tho same manner as the lower unit 52. ~s sl-own in Figures 9-13, tl~e upper active surface inc]udes marginal ridges 61, converging rid~es 62 and ~rough 64 whicll converge in the manner illustrated in Figurcs 10-13 and 16. Gussets 68 join adjacent ridge and trough surfaces of ~he upper active surface 53. The entire active surface 53 ls incised with a,ir slots ~G substantially in tht~ same manner as the active sur-face o the lower unit.

The upper 50 and lower 52 units o~ e pleatcr are shown in Figllres 15 and 16. I~ will appear that tlle plcator UllitS S0 n1ltl 52 converge in the direction of convoyance and llave active ridge and trough surEnccs or uleating ~ilm. Tho uppcr and lower pleater uni~s nest to dc~ine~ a cJencral]y uniEorm (J;l~ or crr~atinCl `

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tne fi.lm. The entirc dock plate surfaces of the upper and lower pleatcr units are pcrforated with air slots 46~or issuing air jets to convey and converge the film ;.n a ~: ~onerally sinusoidal curve.
As is preerred, a pair of side panels 28,30 lie ln confronting converging relation along the li.ne of conveyance between tllc pleater 26 and the chippcr 22 to further squeeze the ilm 12. ~ach side panel inclades a plenum chan~er 70 and a perforated dec]c plate 72. Each . plenum chamber is supplied with pressurized air by means of an air blower 7~ through a tr~nsition cluct 76. L~ach deck p].ate is incised with air slots 4G as shown in Figure 3 Eor issuing air jets alon~ the cleclc pl.a~e surface.
The side panels continue squeeziny or convergincJ the sin-usoidal sh~pe film after it emerges from khe pleater section and as it approaches the chipper.
It is to be understood that the heavy film air conveyor ;~ of the invention may be oriented horizontally, vertically or ~ at any intermediate incline. The air conveyor may be used ; with or witllout the upper pleater unit.
In one use of the invention, 14 mil film was conver~ed by a ratlo of approxima-~ely 5 to 1 omi-tting the upper pleater unit ~nd with 2" ~1.G. air pressure in the entrance and pleater sections and with 3 W.G. in the side panels.
In another use including the upper pleater unit with . a gap o~ 6 inches bet~een pleater units, a convcrgence x~tio . of 7 to 1 was obtained for 14 mil film using the same plenum air pressures as the earlier example.
In ~ach case the air velocity issuing from the air jets is much l~igher tllan film spe~ed so tha~ ~he air conve~or exerts sufficient pull on tlle Eilm to avoid film jamming tlle conveyor d~lring us~.

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Claims (7)

1. An air conveyor for conveying plastic film web of predeter-mined width and indeterminate length comprising an entrance section having a width at least as wide as the film being conveyed, said entrance section comprising a deck plate having slots oriented to issue air jets for conveying the film along the entrance section, a pleater section located downstream of said entrance section, said pleater section comprising air conveyor sections positioned over and under said film web, said over and under sections each having W-shaped deck surfaces in nested confronting relationship to define a gap therebetween having a generally sinusoidal profile extending transversely of the film, each of said W-shaped deck surfaces having slots therein for issuing conveying air jets in the direction of conveyance, means for supplying air under pressure to both the entrance and pleater sections of the air conveyor whereby the air conveyor reduces the width of the film by imparting a generally sinusoidal shape thereto.

2. An air conveyor as defined in claim 1 in which each of said W-shaped deck surfaces comprises at least two troughs separated by a ridge member and further in which the ridge members of one pleated deck surface lie along the trough portion of the other pleater deck section thereby to define the generally sinusoidal profile of said gap.

3. An air conveyor as defined in claim 2 in which the troughs of the pleated deck surfaces increase in depth as said deck surfaces extend in the direction of conveyance.

4. An air conveyor as defined in claim 1 which further includes confronting air conveyor sections positioned on opposite sides of the film for guiding, conveying, and converging the film as it leaves the pleater section.

5. An air conveyor as defined in claim 4 in which the film is reduced in width by a factor of 7:1 between entrance and exit sections of the conveyor.

6. An air conveyor as defined in claim 4 in combination with a grinder for receiving the film as it leaves the conveyor.

7. An air conveyor for conveying plastic scrap film comprising:
an entrance section at least as wide as the film being conveyed, said entrance section having a perforated deck plate and a plenum chamber cooperating to generate air jets for moving the film along the perforated deck, means for supplying pressurized air to said plenum chamber, a pleater section comprising confronting air conveyor sections having deck plate surfaces defining a generally sinusoidal gap therebetween positioned over and under said film web for conveying and reducing the width of the film as it is conveyed, the deck plate surfaces being nested W-shaped surfaces, and means for grinding the film.