US3395426A

US3395426A - Machine for forming random fiber webs

Info

Publication number: US3395426A
Application number: US574379A
Authority: US
Inventors: Howard H Langdon
Original assignee: Curlator Corp
Current assignee: Curlator Corp
Priority date: 1966-08-23
Filing date: 1966-08-23
Publication date: 1968-08-06
Anticipated expiration: 1985-08-06

Description

Aug. 6, 1968 H. H. LANGDON MACHINE FOR FORMING RANDOM FIBER WEBS 5 Sheets-Sheet 1 Filed Aug. 23, 1966 INVENTOR. HOWARD H. LANGDON ATTO RNEY Aug. 6, 1968 H. H. LANGDON 3,395,426

MACHINE FOR FORMING RANDOM FIBER WEBS Filed Aug. 23, 1966 5 Sheets-Sheet 2 INV HOWARD H. LANGDON FIG. 2 BY ATTORNEY 1968 H. H. LANGDON 3,395,426

MACHINE FOR FORMING RANDOM FIBER WEBS 5 Sheets-Sheet 3 Filed Aug. 23. 1966 Ill ' FIG. 3

INVENTOR. HOWARD H. LANGDON BY M ATTORNEY! Aug. 6, 1968 H. H. LANGDON 3,395,426

MACHINE FOR FORMING RANDOM FIBER WEBS Filed Aug. 25, 1966 5 Sheets- Sheet 4 IN VEN TOR. HOWARD H. LANGDON Aug. 6, 1968 H. H. LANGDON MACHINE FOR FORMING RANDOM FIBER WEBS 5 Sheets-Sheet 5 Filed Aug. 23, 1966 FIG.

INVENTOR. HOWARD H. LANGDON ATTORNEY United States Patent 3,395,426 MACHINE FOR FORMING RANDOM FIBER WEBS Howard H. Langdon, Fairport, N.Y., assignor to Curlator Corporation, East Rochester, N.Y., a corporation of New York Filed Aug. 23, 1966, Ser. No. 574,379 11 Claims. (Cl. 19-156.3)

ABSTRACT OF THE DISCLOSURE In the illustrated machine, which is intended to handle short fibers, the fibers are delivered by an air stream between two endless foraminous belts that travel around suction boxes. These belts are disposed With confronting reaches that converge toward one another in the direction of their travel; and they compact the fibers and form them into a mat as the fibers are pulled in between the belts by suction. The mat is delivered between two opening rolls which rotate in opposite directions and at different speeds. An air stream doffs the fibers from these rolls and delivers them onto a foraminous condenser by suction so that they are formed into a random fiber web.

The present invention relates. to machines for forming random fiber webs, and more particularly to machines for forming random webs from short fibers.

Ordinarily short fibers, such as wood fibers, carpet clippings, cotton linters, and the like, are purchased at a fraction of the cost of ordinary textile fiber-s. While short fibers are now being processed through the Rando- Feeder and the Rando-Webber machines built by applicants assignec, and other processing equipment conventional to the textile industry, there are technical considerations, through, that make such equipment inadequate, as compared to the high output rates conventional in processing short wood pulp fibers in the paper processing industry. The paper industry, however, uses water as a medium of suspension and transfer, while the machines mentioned above use air for this purpose. A major factor in the handling of short fibers by air is fiber length. For instance, a one-inch length fiber to be fully encapsulated by air and kept remote from a neighboring fiber in transfer,-would require a one-inch diameter sphere. On the other hand, a short fiber, say onetenth inch .long, would require only a one-tenth inch diameter sphere. In other words, a one-inch fiber when fully encapsulated, would require .5236 cubic inch of fluid, while ten one-tenth inch spheres would require only .05236 cubic inch. Thus, it takes one-tenth times as much fiuid to encapsulate ten one-tenth inch fibers as it takes for one one-inch fiber. v

In usual practice, a staple textile fiber may be three inches long, while the short fibers, to which this invention particularly relates,rnay range from dust to onequarter inch long, although they are not limited to a maximum length of one-quarter inch.

From the above, it will be seen that machinery handling short fibers needs only about one-tenth the circulating air as may be required for handling staple fibers one-inch long, and that for a three-inch long fiber there is required two hundred and eighty-three times the air required for encapsulation of ten one-tenth inch fibers.

While in practice it is likely that a complete encapsulation is not necessary and that only a fraction of the air is used that would be required for complete encapsulation, nevertheless it will be obvious from the preceding discussion that a machine built to handle short fibers can be of simplified and more compact configuration than machines for operating on long, staple fibers, so far as air requirements are concerned.

Another advantage in operating on short fibers is the relatively low requirement for opening the fibers. With long fibers of small denier or diameter, the process of disengagement of fibers from one another is a major factor in design and quality of the product. In the formation of random fiber webs, opening, and increasing the air to fiber ratio are of prime importance.

Other factors relating to the handling of short fibers are that for such fibers the air stream function not only as a dofiing and conveying medium, but that the distance between doffing from the lickerin and the condenser can be of reduced length since it need be only sufiicient to allow for the fibers to turn about infiight to arrange themselves in a random fashion on the condensing screen. In the short fiber web former the advantage of the small requirement of air as a medium of transfer, the short travel to the condensing screen, along with the freedom of individual fibers to reorient will help eliminate air stream turbulence pockets and make more compact the necessary mechanical structure.

Another advantage associated with designing and manufacturing a short fiber machine as compared to one of conventional form, for forming random fiber webs, is that the air bridge principle of Patent 0N. 2,744,294 may be incorporated in the web former while at the same time simplifying the design and construction. 7 One object of the invention is to provide a machine by which the production rate of fiber web formation may be increased as compared to the production rate realized in conventional machines for forming textile fiber webs.

Another object of the invention is to provide a practical machine for producing random fiber webs from short fibers such as wood fibers (kraft, chemically-cooked, bleached and unbleached), carpet clippings, cotton linters, and other relatively short fibers.

Another object of the invention is to provide a machine on which the widthwise uniformity of mat formation of a random fiber web may be improved as compared with conventional machines used for this purpose.

Another object of the invention is to provide a machine for forming random fiber webs, which will include means for effecting fiber opening, storage and transfer ducts suited to high production rates with short fibers, and the air bridge principle for effecting uniform mat formation.

Another object of the invention is to provide apparatus for manufacturing at relatively high rates of speed of fiber webs from wood and other short fibers for paperlike products, sanitary and surgical items, batting from shortlow-grade waste fibers such as card strips, card and picker waste, etc.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in connection with the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation, with parts broken away, of apparatus for forming a random fiber web of short fibers, including a fiber opener, fiber storage bin, at random fiber web former built according to one embodiment of this invention, and connecting parts; FIG. 2 is a vertical sectional view on an enlarged scale through the fiber web former shown in FIG. 1;

FIG. 3 is a front elevation, partly broken away, showing one of the condensing screens of the apparatus of FIG. 2 and associated parts;

FIG. 4 is a vertical sectional view, showing diagrammatically a machine constructed according to another embodiment of the invention; and

FIG. 5 is a vertical sectional view of a machine constructed according to a still further embodiment of the invention.

In all of the illustrated embodiments of the invention, fibers are delivered by an air stream between two endless foraminous belts that travel around suction boxes. The upper juxtaposed reaches of these belts converge downwardly (that is, in the direction of their travel), toward one another and they compact the fibers and form them into a mat as the fibers are pulled in between the belts by the suction. The mat is delivered from between the belts to two opening rolls which have teeth that are oppositely inclined and which rotate in opposite directions and preferably at different speeds. The fibers are then carried by a suction-produced air stream onto a foraminous condenser belt which also travels over a suction box, and are laid down in random fashion on this condenser belt, thereby being formed into a random fiber web.

Referring now to the drawings by numerals of reference, and first to FIG. 1, the apparatus here shown involves not only a high speed web former, but also a system for pre-opening the stock, a storage facility, a feeding unit at the bottom of the storage unit, and a system of piping for pneumatically conveying the fibers from storage to the web former along with a return of fiber and air back to the top of the storage unit. Other components include a revolving screen condenser for dropping returned fiber back to the storage bin, a centrifugal separator for cleaning and returning the circulating air to the starting point, air control valves, and a component part of the air bridge structure located in the pneumatic transfer line.

In FIG. 1, denotes a conventional opener by which the fiber is pre-opened from sheet stock or from bales. For baled sheet board a hammermill type opener would preferably be used to open and fluff the stock. For baled dry pulp or other kinds of short fibers, hammermills, or other conventional openers may be employed.

The stock is delivered to the opener 10 by, for instance, a conveyor belt 8. The opened and fluffed stock is pneumatically conveyed from the opener through piping 12 to a storage bin or tank 14, where the stock may drop out for storage, or a fraction of the stock may proceed across the tank or bin and continue with the air stream through a pipe 16 to a conventional metering valve 18. To agitate the fiber in the storage bin 14 and facilitate its feed into the system leading to the web former or formers, a grill plate 15 (FIG. 1) is pivoted at its lower end on a shaft 17 in the bin 14, to be rocked up and down by a motordriven crank arm 19 which is connected by a link 21 to the plate 15.

The fiber flows out of the storage bin 14 through a fiber feed box of conventional construction denoted as a whole at 18, and including a conventional metering valve for controlling the rate of flow. It passes from the feed box into a pipe to the air bridge and diffuser denoted as a whole at 22. If the web former 40 is not at the moment demanding fiber, the total airborne fiber proceeds through the return pipe 24 to a revolving screen condenser 26 and is returned to the storage tank 14. The transfer air passes through the condenser screen and pipe 27 to a conventional centrifugal separator 28. This centrifugal separator, which may be of conventional construction is used to further clean the air before exhausting a minor fraction to atmosphere through pipe 30, or to a dust box, or to a conventional filter to thoroughly clean the air. The major portion of the air enters the hammermill or other opener, such as a Rando-Cleaner opener made by the assignee of the present application, through the pipe 32.

The transfer air for the system is assured of the quality and velocity of travel to obtain fiber transfer by means of the fan action within the hammermill 10 itself or the opener, by means of a motor drive and fan within the centrifugal separator 28, and by means of a fan 36 associated with the web former 40, the exhaust of which may be returned to the diffuser 22 through a pipe 37 which extends into pipe 24 and opens through nozzle 41 into the pipe 24. The web former is of the Width required to deliver the desired width of web. Moreover, the pipe 24 may be part of a duct work system such as disclosed in applicants pending patent application, Ser. No. 521,267, filed J an. 18, 1966, which feeds a plurality of web formers.

The cleaned air for recirculation enters the system through the opening unit 10 and enters the top section of the storage unit 14 tangentially for centrifugal flow-out from a separator 38. The velocity of the air is materially reduced in this unit allowing a dropout of the majority of the fiber into storage. However, a minor fraction of fiber will travel with the air to enter pipe 16 which again enters the fluidizing valve 18 at the bottom of the storage tank; and air with the fiber enters the pipe 20.

At the web former 40, a major part of the fiber and air enters the feed section of the former by suction of the fan 36, but only upon demand, as will appear hereinafter. The air thus subtracted is returned at the diffuser 22 and continues to the condenser 26, separator 28, and thence back to the beginning at the hood of the opener 10. A back pressure valve 42 is needed in the separator air outlet 30. The purpose of this valve is to permit escape of any excess air leaking into the system.

The fiber returning from the condenser to storage also passes through the conical member 38 and its rate of fiow is controlled by a manually operable conical control valve 39.

A gear motor 99 mounted on top of the storage bin 14 and connected in any suitable manner to the rotary condenser 26, drives this condenser.

The web former itself is constructed as shown in FIGS. 2 and 3.

This unit consists essentially of three parts: (1) the feed function which works in cooperation with the air bridge diffuser 22, (2) the opening cylinders, and (3) the condenser section. The feed function comprises two

suction boxes

44 and 46, which are mounted in a housing 48 and which are angularly adjustable with reference to one another in the housing and are secured in adjustted position by bolts 50 for

box

44 and 52 for box 46, which pass through

slots

51 and 53, respectively, formed in

wings

54 and 55, respectively, projecting from the upper and lower corners of the boxes.

The two suction boxes are open at their confronting faces; and endless traveling screens 60 and 61, respectively, surround these boxes. The screen 60 travels over

rolls

62 and 64; and the screen 61 travels over

rolls

63 and 65. The

rolls

62 and 63 are journaled in

slots

66 and 67, respectively, formed in opposite ends of a yoke member 68 that is secured to one side wall of the housing 48 by a screw 70 which passes through an inclined slot 72 in the yoke member 68, and threads into the side wall of the housing 48.

The

rollers

64 and 65 are perforated rollers and are journaled in slots or pockets 74 and 75, respectively, formed in an irregularly shaped yoke type plate 76 in the housing 48. Mounted in

pockets

78 and 79 also formed in the plate 76 are

other rolls

80 and 81, which act as clearer rolls, as will appear hereinafter. The clearer rolls 80 and 81 are provided to clear the

screen cylinders

64, 65 of deposited fiber that does not otherwise clear. The

screen cylinders

64, 65 may also have open ends for facilitating ingress of air to them.

The suction in the

suction boxes

44 and 46 is produced by the fan 36 (FIG. 1), which causes air and fiber to be withdrawn from the air bridge diffuser 22. The suction side of this fan is connected to the

outlets

47 and 49 in the sides of the

suction boxes

44, 46. The suction boxes are adjusted angularly to one another so that the traveling

screens

60 and 61 converge downwardly toward one another on their forward reaches. Thus, a tapered downwardly diminishing space or trumpet is formed between and by the forward, juxtaposed reaches of the

screens

60, 61. This space will fill up with fiber until the fiber therebetween chokes off the air flow from the air bridge diffuser 22. Then, no further delivery of fiber would take place unless the screens were activated to move the fiber between them downward so that space is provided for further inflow of air and entrained fiber.

The air bridge 22 is so constructed that fibers does not enter the downtake pipe 23 to the trumpet by the force of gravity but only when the

screens

60, 61 have sufficient uncovered area that the flow of air toward the web former will carry the fiber to the trumpet. The principle involved is the same as in prior Patent No. 2,744,294 above mentioned.

Rotatably mounted below the

rollers

64 and 65 are two

rotating cylinders

90, 91 which have toothed peripheries. Cylinder 90 rotates clockwise, while cylinder 91 rotates counterclockwise. Cylinder 90 may turn 1500 to 2500 or more r.p.m. while cylinder 91 may rotate 500 to 1000 r.p.m. The teeth on the cylinder 90 are opposed in direction to the teeth on the cylinder 91. Thus, there is a differential between the surface speeds of the cylinders along with opposing teeth as the respective tooth surfaces approach the nip. The incoming fiber fed down from the

screens

60, 61 is therefore acted upon, and forced to pass through the nip at the same time that work is being done to open any compacted fiber that approaches the nip. The downward faces of the teeth of the cylinder 91 carry the fiber through while the upward facing teeth of the cylinder 90 hold the fiber back, while cylinder 90 rotates in such direction as also to carry the fibers downwardly like cylinder 91. The flow rate of the fiber through the nip can be regulated by the number of teeth per inch, the height of the teeth, etc. along with the clearance between the tips of the teeth of the respective cylinders. Allowance must be made, however, for a reasonable amount of air to pass through the nip to aid in doffing the fibers from the rotors. The cylinder 90 is mounted on a shaft 106 that is journaled at its ends in eccentric bearing members 108 that are rotatably adjustable in the side walls of the housing to control the distance between the teeth 92 and 93 at the nip.

It should be noted that the

screen cylinders

64 and 65 are perforated. The screens themselves may be made of fourdrinier wire, and, therefore, are also porous. Air can be drawn into the area above the roll nips which, aided by the condenser suction from a suction box 95, that is mounted in the base of the former, will further aid in clearing and doffing the rolls.

Mounted in the suction box 95 in the base of the former are two

pulleys

96 and 97 over which travels an endless screen belt 98. Pulley 96 is the drive pulley and may be driven in any suitable manner, as, for instance, through a conventional variable speed motor. Drive pulley 96 is journaled in a recess 110 in the base of the housing; and driven pulley 97 is journaled in a recess 112 in the base of the housing.

In order to assure dofling and to direct the air and fibers within desirable bounds onto the condenser screen, the dofiing bars 99 and 100 are provided.

It is well known in the textile industry that for any rotating cylinder a film of the surrounding medium-in this case airwill also revolve with the cylinder. The successive layers or laminae of this so-called bound layer diminish in velocity until the outer layers have negligible velocity. There is, however, a strong likelihood of more or less turbulence being generated in the surrounding atmosphere where the surrounding atmosphere is in the gaseous or liquid state. To avoid this, the dolfing bars 99 and 100 are extended toward the

condensers

90, 91 so that the bound layers can reform behind the dofiing bars without drawing air and entrained fiber from the main stream of air and fiber that travels from the nip to the condenser 98.

The fibers are doffed from the

cylinders

90 and 91 by the doffers 99 and 100, which are secured in the housing 48 and disposed in operative position to the

cylinders

90 and 91, respectively. The fibers are drawn onto the screen belt 98 by the suction of the fan 36 which is mounted in the bracket 102 that is removably held in position in the housing by the screws 104.

Mounted above the upper reach of the condenser screen belt 98 is a web roll 114 which is mounted on a shaft 116 that is joumaled eccentrically in bearings 118 that are adjustable to control the distance between the periphery of the web roll and the screen. This roll 114 may be driven in time with belt 98 by any suitable means. A doffing bar 120 that is secured to one wall of the housing 48 adjacent the periphery of the web roll prevents the web from following around the roll as the roll rotates, and compels it to travel with the condenser belt.

The web roll 114 acts as a seal and lloats freely in the vertical plane. Its purpose is to seal against atmospheric pressure in order to maintain a sub-atmospheric pressure within the suction box 95. The web roll also compacts, more or less, the issuing web of formed fibers.

A bracket 124 (FIG. 1) is secured to the base 112 to project laterally from one side thereof. It carries a pulley 126. An endless belt 128 which travels over this pulley and over a pulley 130, that is mounted coaxially with pulley 97 to rotate therewith, carries the product web W out of the machine.

It will be noted that the web formed 48 has three

screen boxes

44, 46, that differ mainly in physical size. In each case the suction box, its rolls, screen and belt alignment parts will be integrated so :far as possible into removable units for screen replacement and maintenance.

In each case, the condenser unit is a. complete structural unit that may be lifted into the web forming machine, locked in place, and its drives connected all with the least time and effort. It may be removed in the reverse manner. To obtain structural stability the

screen box

44 or 46 is of sheet steel of a weight suited to its width. It is formed from a single sheet and welded to the end plates 132, 134 (FIG. 3). Each end plate will be provided with a

suction air outlet

136, 138, respectively. The end plates will also be of such length and configuration that the screen may be removed endwise. The

rolls

62, 63, 64, 65 will be fitted with through shafts for removal.

The

belts

60, 61, rolls 80, 81,

rollers

90, 91, belt 98, and roller 114 may be driven in any suitable manner as, for instance, by one of the motors above mentioned through any suitable gear drive.

For the screens it is intended to use fourdrinier wire cloth such as used in the paper industry. The surface velocity of the wire cloth will be higher than when processing dry standard fiber length random webs. However, the surface velocity will be much lower than used in the wet processing of paper where the water flowing through the screen has some lubricating effect when running over the bearing plates of the suction boxes. A surface velocity of the screens in the neighborhood of 400 feet per minute, more or less, will be used in the machines of the present invention. In the paper industry the velocities may run as high as 3000 feet per minute. For the condenser screen 98, velocities higher than 400 feet per minute may be used, however.

Wear strips 139 may be provided under the traveling screens to support them.

One feature of the apparatus shown is the means for self-alignment of the screen belts. The upper screen roll 63, for instance, is pivoted in such manner that when shifted endwise the center distance between shaft centers is diminished on one end as compared to an increase in center distance on the opposite end. The tendency of the screen belt is to travel endwise when the supporting shafts are not parallel. There are several devices on the market for centering belts between rolls. In general, these prior units use a skew roll and provide a certain degree of wrap on this roll and include fingers riding along the edge of the belt which through power application shift the skew roll in such a manner that the belt is tightened on one side and loosened on the opposite side. This effect is achieved in the apparatus illustrated by mounting the upper roll pivotally by linkages 140 (FIG. 3). Each link 140 is mounted at one end on the ball head 142 of a stud 144 that is welded at its foot to the

plate

132 or 134. At its other end, each link 1 40 is mounted on a ball joint 146 formed intermediate the ends of an extension of the shaft 148 on which the

respective roll

62, 63 is mounted. The link members 140 permit tightening the

screen belts

60, 61 and adjustment of the

rolls

62, 63 for parallelism.

A double thrust bearing including an intermediate ring 143 with yoke pins and a nut to apply the thrust force help to maintain the screen belt alignment widthwise. There are several devices on the market that can provide the signal to shift the roll shaft 148, when required, through the thrust bearing and pinned collar and yoke 143.

The

shafts

148, 150, on which rolls 63, 65 are mounted, pass through

collars

152, 154 which are welded to the

end plates

132, 134, respectively. The collar 152 on the end plate 132, drops into a cup or slot of a support column 156, while the collar 154 is slipped sidewise into a slot in the support column. This permits adjustment of the trumpet configuration.

In the modification of the invention illustrated in FIG. 4, the fiber is delivered to the machine, which may be one of a series of like machines, from an air and fiber circulating duct 170.

The duct has a deflector 172 in it beneath which the fibers and air pass to the two

belts

174 and 175, which in this case are non-porous. The belt 174 travels over rollers 176 and 178, while the belt 175 travels over rollers 177 and 179. The rollers 178 and 179 are of different diameter, and in the instance shown, the roller 178 is larger so that if the two rollers 178 and 179 are driven at the same speed, the belt 174 will move faster than the belt 175. The belts are disposed so that their inner, juxtaposed reaches converge downwardly to compact and feed the fibers downwardly. Toothed rollers 182, 183 are disposed adjacent the peripheries of the rollers 178 and 179 to pick the fibers off the

belts

174 and 175, and to form a nip through which the fibers are fed downwardly. Preferably, toothed roller 183 is driven at a faster speed than toothed roller 182 and in the opposite direction. Toothed roller 183 may be driven counterclockwise, for instance, at a speed of 500 to 1000 r.p.m., while toothed roller 182 may be driven at a speed of only 100 to 500 rpm.

Beneath the rollers 182, 183 is a condenser screen belt 185 which is an endless belt and travels over pulleys, only one of which is shown at 187 The upper reach of screen belt 185 travels over the top of a suction box 188. A suction fan 190 is connected to the suction box by a duct 192. The fan is driven by a variable speed motor 194. The return duct 196 from the fan leads back to the circulating duct 170 under a deflector 198.

Brushes

200, 201 are provided to remove from the

belts

174 and 175 loose fibers that may be carried upwardly on the return reaches of these belts. A brush 203 may be mounted above the screen belt 185 to remove loose fibers from that screen. This belt travels on its upper reach from right to left.

Brushes

205 and 207 may be mounted beneath the screen belt 185 to remove from the screen any fibers that may pass through the belt.

A roller 208, that is journaled on the shaft 210 in the housing, is mounted to be adjustable up and down on the housing to control the density of the web laid down on the condenser screen belt 185.

Guards

212 and 213, which are bolted to the housing by bolt and nut combinations 214, are formed at their upper ends with arcuate top surfaces following closely the contours of the rollers 178, 179, but are spaced sufliciently from the

belts

174, 175 to allow air to flow in between the guards and the belts to supply the suction box 188.

The return duct 196 provides a return for air and fiber that passes the condenser screen 185. The air and fiber so returned are carried by the circulating duct 170 onto other machines in the line, or back to the storage bin from which the fibers were fed initially.

The

belts

174, 175, roll 208, rollers 182, 183, and belt may be driven from a motor or motors (not shown) in any suitable manner.

A further modification of the invention is shown in FIG. 5.

Here a hopper, shown fragmentarily at 220, supplies fibers between the feed rolls 222 and 224 which are journaled in the side wall 226 of the condenser unit 230.

Mounted below and to one side of the

rollers

222, 224 are two

suction boxes

232 and 234. Rotatably journaled in the upper suction box 232 are two

pulleys

236 and 238. An endless condenser screen belt 240 travels over these pulleys, one of which may be driven by a motor in any suitable manner. The suction box 232 is connected through the opening 242 and a duct, which communicates with that opening, to a suction fan. A bar 244 which extends crosswise of the unit, and which has a sealing member 246 at its upper end which contacts the periphery of the roll 224 and the sealing member 248 at its lower end, which contacts the belt 240, serves to make the connection between the belt 240 and the feed roll 224 airtight.

Mounted in the lower suction box 234 are two

pulleys

250 and 252 over which there travels an endless condenser belt 254. One of the pulleys is the driver and may be driven by a motor (not shown) in any suitable manner. A suction fan is connected to the suction box 234 beneath the lower reach of the condenser belt 254 by a duct that communicates with the opening 256 in the suction box. The rubber seal or gasket 258 engages the condenser screen as it travels over the periphery of the pulley 250 to seal at that point while a rubber seal 260 which is connected to a plate 262 in the unit serves to seal at the point where the lower reach of the condenser belt rides onto the pulley 252.

The suction boxes pull air and fibers in between the feed rolls 222 and 224 and carry the fibers into the trumpet formed between the upper juxtaposed reaches of the

belts

240 and 254, thereby constituting an air bridge. The fibers are compacted between the confronting reaches of the

belts

240 and 254 and are carried off the belts by opening

rolls

264 and 266, which are provided with opening

fingers

265 and 267, respectively, which open the mat delivered from the trumpet. The fibers are then carried on down to the main condenser belt 270, which travels over pulleys 272, one only of which is shown. This belt travels around a condenser box 275, which has a suction opening 274 in it that is connected by duct (not shown) to a suction fan, so as to pull the fibers down onto the suction belt. The belt 270 delivers the web so formed, as in the previously described embodiments of the invention.

Dirt and debris are too heavy to be carried by the air bridge from the

rolls

222, 224 to the trumpet between

belts

240, 254, but drop out of the air stream through the duct 276 formed between the plates 277, 278 into a dust bin 280 in the bottom of the unit.

While the invention has been described in connection with several different embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, th principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention what I claim is:

1. A machine for forming a random fiber web comprising two spaced, endless foraminous belts disposed to have confronting reaches which converge in the direction of movement of these confronting reaches,

means for imparting movement to said belts,

means for creating air streams between and through said belts to deliver fibers from a source of opened fibers directly between said confronting reaches whereby in their movement said confronting reaches form a single mat,

a pair of rotary spaced, imperforate toothed rolls disposed in operative relation to said belts at the ends toward which said confronting reaches converge,

means for rotating said rolls in opposite directions simultaneously to pick fibers from the mat and force said fibers to pass through the nip between said rolls,

a movable condenser,

means for moving said condenser, and

suction means for creating a single air stream through the nip between said rolls and through said condenser pneumatically to doff fibers from said rolls and deposit them in random fashion on said condenser.

2. A machine as claimed in claim 1, wherein the teeth of said rolls face in opposite directions.

3. A machine as claimed in claim 1, wherein said rolls are rotated at different speeds.

4. A machine as claimed in claim 3, wherein one of the rolls is eccentrically mounted so as to be adjustable toward and from the other roll to control the distance between the rolls at the nip.

5. A machine as claimed in claim 1, wherein the two belts are disposed to surround and travel around two separate suction boxes, means are provided for adjustably mounting the suction boxes in the machine for angular adjustment of the boxes relative to one another to vary the inclination to one another of the confronting reaches of the belts, thereby to vary the angle at which said confronting reaches converge in the direction of their movement, and means is provided in the suction boxes for creating a suction to draw air through the confronting reaches of the respective belts into the interior of the respective boxes.

6. A machine as claimed in claim 1, wherein said condenser comprises a third endless foraminous belt, means for effecting travel of the upper reach of the condenser belt in a direction transverse to the directions of movement of the two first-named belts, and means for creating an air stream of dotf fibers from said toothed rolls and deliver them onto the upper reach of said third belt.

7. Apparatus for forming a random fiber web comprising an air duct, means for creating a stream of air in said duct to convey fibers in suspension through said duct, and a fiber web former communicating with said duct and comprising a pair of endless foraminous belts disposed to have confronting reaches converging in the direction of their movement, means for sucking air and fibers from said duct into the space between said confronting reaches and for sucking the air through said confronting reaches thereby to cause deposit of the fibers on said confronting reaches, means for effecting movement of said belts to move the deposited fibers in the direction of convergence of said confronting reaches and to compact the fibers and form them into a mat, a pair of spaced, imperforate rotary toothed rolls disposed adjacent and in operative relation to the foremost ends of said confronting reaches to comb fibers from the mat, means for driving said toothed rolls in opposite directions, a third endless foraminous belt disposed beneath said toothed rolls, and means for sucking air and fibers through the nip between said rolls and for sucking air through the upper reach of said third belt to cause deposit of the combed fibers in random fashion on the upper reach of said third belt, and means for effecting movement of said third belt.

8. Apparatus as claimed in claim 7, wherein said toothed rolls have teeth facing in opposite directions, and the means for driving them drives them at different speeds.

9. A machine for forming a random fiber web comprising a pair of inclined endless foraminous belts disposed to have their forward reaches confronting and converging in the direction of their movement, means for delivering fibers to said machine adjacent the upper ends of said belts to one side thereof, means for creating a stream of air to convey air and fibers from the point of delivery of the fibers into the space between said belts and for sucking air through the confronting reaches of the belts to deposit the fibers on said confronting reaches, means for effecting movement of said belts to move the fibers downwardly and to compact them between said confronting reaches and form them into a mat, rotary two spaced, imperforate, toothed rollers disposed adjacent the lower ends of said belts to comb fibers from the mat, a movable foraminous condenser disposed beneath said rollers, means for rotating said rollers in opposite directions and at different speeds, respectively, and means for sucking air between the nip of said rollers into said condenser to transport the combed fibers from said rollers and deposit them on said condenser.

10. A machine as claimed in claim 9, wherein means is provided directly beneath said delivery point to catch material falling out of the first-named air stream because it is too heavy to be carried thereby.

11. A machine as claimed in claim 9, wherein said conde nser is a third endless foraminous belt, and each endless belt is mounted to travel around a suction box, and means is provided in each suction box between the upper and lower reaches of its belt to suck air through the belt.

References Cited UNITED STATES PATENTS 1,233,514 7/1917 Scott 19-82 1,349,351 8/1920 Waling 156-377 1,740,990 12/1929 Mackenzie 19-156.4 2,317,895 4/1943 Drill 156377 2,691,553 10/1954 Pettigrew 308-62 2,715,755 8/1955 Jones 19-156.3 2,744,294 5/ 1956 Buresh et a1. 19-202 2,941,264 6/1960 Fleissner 19-156 FOREIGN PATENTS 462,872 7/ 1928 Germany.

MERVIN STEIN, Primary Examiner.

I. C. WADDEY, Assistant Examiner.