IL37203A - Apparatus for producing a nonwoven fibrous element having a highly uniform deposit of the fibers - Google Patents

Description

This invention relates generally to the manufacture of non-woven fabrics and more particularly to the manufacture of such products by substantially dry procedures.

One common scheme for manufacturing non-woven fabrics involves delivering a slurry of air and fibers through a single large venturi to a rotating perforated drum. The1 we that is deposited on the drum is picked off and conveyed to subsequent processing stations for the addition of binder and other operations. While the single venturi is efficient in delivering the fiber slurry to the perforated drum, it accomplishes continuous stream deposition and does not afford an opportunity for multi-pass scanning of the drum surface. Hence, the non-woven web produced in this prior art manner is subject to irregularities in the thickness or weight of the product] and variations in the other physical properties of the web iikewiee obtain.

Therefore, an important object of the present invention is .to provide apparatus which produces a non-woven fabric that is characterized. by a highly uniform deposit of the fibers.

A more general object of the invention is to provide new and improved apparatus for producing a non-woven fibrous element ; \ Another object of the invention is to provide apparatus for producing a non-woven fabric which includes means for directing a plurality of commingling streams of fibers toward a collecting surface.

Additional objects and features of the invention pertain to the particular structures and arrangements whereby the foregoing objects are attained.

This Invention, both to its structure and its mode of o re ce to the ft Pig. 1 is a side elevational view in longitudinal section of apparatus for producing a non-woven fabric, constructed in compliance with the principles of the present invention; Pig. 2 is a top plan view of the apparatus of Pig. 1, shown with portions of certain elements broken away in order to reveal details of construction; Pig. 3 is an enlarged perspective view of the stationary, fiber-delivery di ct utilized in the apparatus of Pigs. 1 and 2; Pig. 3a shows the stationary duct rotated to compensate for belt velocity; Pig. 4 is a perspective view, of the fiber-delivery discharge orifice unit used in conjunction with the' stationary duct of Fig. 3, being shown in intermediate scale; Pig. 5 is a reduced scale showing'of a modified delivery duct for use in the apparatus of the invention; Pig. 6 is a bottom view of the duct of Pig. 5j Pig. 7 is a side elevational view of a further modified delivery duct useful in the practice of the invention; and Pig. 8 is an enlarged, fragmentary, perspective view showing actuation of one of the louvers used with the duct of Pig. 7.

Referring now in detail to the drawings, specifically to Pigs. 1 and 2, apparatus for producing non-woven fabrics is indicated generally by the reference numeral 10 and comprises a foraminous member 12, a suction plenum 14, a fiber supply unit l6 and a fiber delivery arrangement 18. The foraminous member 12 comprises a belt and includes a planar work station for collecting a fiber deposit, this planar work station being located generally between a horizontal, upstream line 20 and a horizontal, generally downstream line 22 spaced apart from the line 20.

The suction plenum 14 confronts the lower surface of this work section for exhausting a carrier fluid such as air therethrough, and the fiber delivery unit 18 is disposed generally confronting the upper surface of this work section to cooperate with the" suction plenum and the foraminous belt in producing a non-woven fibrous web.

The foraminous belt 12 is selected to be a flexible, endless member which is threaded over a powered head pulley 24 and an idler, tail pulley 26. The tail pulley 26 is mounted on a shaft 28 which rotates freely in Journals 30, the starboard journal being supported on a mounting block 32 and the port journal being fastened to a standard 34. Correspondingly, the head pulley 24 is mounted on a shaft 36 which is rotatably mounted in journals 38, the starboard journal 38 being fastened to an upright mounting block 40 and the port journal" being secured to a corresponding mounting block 42. ' In order to impart motion to the belt 12 in the direction of arrows 44 , the shaft 3 of head pulley 24 is coupled in an electric drive motor 46 through a speed reducer 48. The housings of motor 46 and speed reducer 48 are welded or otherwise suitably fastened together, and the motor housing is fastened to a mounting block 50 to support the drive units. x The suction plenum 14 includes an exhaust box 2 which is secured between fore and aft supports ^ and 56 ; and a suction pipe 58 is connected to the exhaust box 52 to communicate with the interior thereof for withdrawing carrier air through the belt 12. A generally semi-cylindrical housing or shroud 60 is 'also mounted between the supports ^ and 56. However, the shroud 60 is situated overlying the belt 12 and generally in vertical alignment with the exhaust box 52. A suspension of the interior of shroud 60 through a stationary duct 62 which comprises the terminous of the fiber supply unit 16. In order to direct the suspension of fibers toward the belt 12, the stationary duct 62 is provided with a longitudinally extending, downwardly facing outlet 64 ; and as is shown in Pig. 3, the outlet 64 is wider at its upstream end than at its downstream end. In addition, the outlet 64 is arranged to be adjustably tapered from its upstream end to its downstream end by means of a flexible shutter blade 65 which is attached to the duct 62 by slot-and-set-screw arrangements 65. The longitudinal extent of the outlet 64 is selected to coincide generally with the width of the belt 12, as is best shown in Fig. 2. So arranged, the outlet 64 is capable of delivering a uniform quantity of fibers to each width portion of the belt 12.

In compliance with the features of the present invention, the apparatus 10 includes means for directing the fibers emanating from the duct 62 into a plurality of flows scanning the work section of the - foraminous belt 12. In the illustrated embodiment, the fiber delivery arrangement l8 includes a plurality of arcuately spaced discharge vanes 66 which are appropriately spaced from the belt 12 and which define fiber delivery orifices therebetween.

As is best shown in Fig. 2, the vanes 66 are mounted between a pair of annular end plates 68, and a pair of axially extending collars 70 and 72 are fastened to the respective end plates 68. The vanes 66 are intended to be rotated past the outlet 64 of stationary duct 62; and in order to facilitate this rotation, the collar 70 is situated in an annular bearing 7^ which is fitted into an end face of the shroud 60. Similarly, the collar 72 is rotatably mounted in an annular bearing 76 which is fitted collar 72 Is fashioned to include a pulley portion 78 which is drivably coupled to a variable speed electric motor 80 by means of an endless drive belt 82 and a drive pulley 84 which is mounted on the output shaft of motor 80. The motor 80 is conveniently fastened to the standard 5 by bolts 86 or other suitable means; and the standard 54 is made rigid by means of a diagonal brace 88 and a foot plate 90· The vanes 66 are curved so as to direct the exiting fibers in a direction generally tangential to the cylinder defined by the tips of the vanes. Furthermore, the motor 80 is arranged to rotate the vanes 66 and the discharge orifices defined therebetween in a direction opposite to the tangential vane direction and i,n the direction indicated in Pig. 1 by the arrow 92. The discharge orifices defined between the vanes 66 are thus caused to scan the surface of the work section whereby to deposit a layer of fibers which is of highly uniform thickness and weight. While proper selection of the speed of rotation of the vanes 66 , by means of controlling the speed of motor 80, will cause the fibers to move in a direction radii al to the duct 62 and at a reduced speed, selecting different speeds of rotation will cause the fibers to move at different .angles to the radial direction. In this manner, fiber migration inducing horizontal velocities parallel to the deposit surface of belt 12 are avoided or minimized.

The apparatus of the invention additionally includes support jokes 9 for the stationary duct 62 and an auxiliary conveyor 96 for transferring the deposited web of fibers to subsequent processing stations for the addition of binder and such finishing operations as printing, cutting and packaging. The duct 62 may b? rotated in the Jokes '+ to compensate for Having thus described one construction of the apparatus of the invention, it will be valuable now to set forth the manner in which the illustrated embodiment operates.

A continuous stream of suitably opened fibers suspended in a carrier fluid such as air will be supplied to the stationary duct 62; and numerous types of fibers may be employed, such as wood, cotton, synthetic cellulose, asbestos, glass and various synthetic polymers. These fibers are opened to the point where each fiber is separated from the others. Long staple fiber can be fluffed up and separated by well-known devices such as cards, garnets and opening pickers. On the other hand, wood cellulose, usually provided in sheet form can be opened by disc grinders and hammer mills.

The fiber-air slurry entering the duct 62 passes through the outlet 64 and encounters the rotating vanes 66, the vanes 66 separatin the fiber-air stream into a multiplicity of separate flows while directing these flows to scan the surface of the moving foramlnous belt whereby to achieve a highly uniform deposit. The air carrying the fibers through the duct 62 is exhausted by the suction box 52 and may be recycled. This suction aids in the transport of the fibers as well as the rapid and efficient depositing thereof. The deposited fibers pass from beneath the shroud 60 as an integrated web 8 which may be readily handled and conveyed to subsequent processing stations While a particular embodiment of the invention has thus far been shown and described, it should be understood that the invention is not limited thereto and that many modifications may be made. Therefore and in order to enhance the understanding of the invention, certain modified embodiments thereof have- been Illustrated in Figs. 5-3, these modifications The adjustable outlet 64 of the embodiment of Figs. 1 -4 is able to achieve good cross-machine direction distribution of fibers and air by building up a relatively high pressure differential between the inside of the duct and the outside thereof. It is, however, desirable to keep flow velocities as nearly constant as practicable; and while the uniform lumen duct 62 exhibits varying velocity from the upstream to the downstream end of outlet 64, the embodiments illustrated in Figs. 5-8 show various alternatives.

Referring to Figs. 5 and 6, a stationary duct 62a is arranged for cooperation with a foraminous belt of ' comparatively narrow width. Specifically, the duct 62a is provided with an outlet comprising a uniform width slot 100, a conduit section 102 of comparatively large cross-sectional area nd^ a tapering throat 104 which communicates the conduit 102 with the slot 100. Furthermore, and as is best shown in Fig. 5i the slot 100 is deeper at its upstream end than at its downstream end, the slot 100 having a root 106 which follows a continuous curve from the upstream to the downstream end. By these arrangements, the slot 100 promotes a substantially uniform velocity of the fiber and air suspension ^throughout its length.

In Figs. 7 and 8 , a stationary duct 62b is arranged for cooperation with a foraminous belt of considerable width. In particular, the duct 62b is provided with means for splitting the flow through a uniform width outlet .64b whereby to allow the effective delivery area of each outlet portion to be increased or decreased. Specifically, each of a suitable number of curved louvers 108 is pivoted' to the surface of duct 62b by means of a pivot rod 110 and mounting brackets 112. louver 108 and is passed beyond the end of duct 62b for facility in manipulation of the louvers. As will be appreciated, the outlet 64b provides a uniform yet adjustable discharge along its length.

The specific embodiments herein shown and described are to be considered as being primarily illustrative. Various changes beyond those described will, no doubt, occur to those skilled in the art; and such changes are to be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims. \

Claims (2)

1. 37205/2 WHAT WE CLAIM IG:- 1. Apparatus for producing a non-woven fibrous element comprising: a foraminous member, including a work section for collecting a fiber deposit; suction means confronting one surface of said work section for exhausting a carrier fluid through said section; supply means for providing a quantity of fibers suspended in a carrier fluid; and fiber delivery means generally confronting the opposite surface of said work section, j connected to the outlet end of said supply means and including a plurality of arcuately spaced discharge orifices and drive means for rotating said discharge orifices whereby to cause said orifices to scan the surfa.ee of said work section and deposit a layer of fibers thereon.
2. 2. Apparatus according to Claim 1 wherein said foraminous member comprises a flexible, endless belt; wherein said work section is planar; and wherein. said apparatus further includes means for causing continuous, longitudinal movement of said belt whereby to produce a substantially endless fibrous web. . 1 3. Apparatus according to Claim 1 or 2 wherein said supply means includes stationary duct means disposed at said delivery means, said duct means having a longitudinally extending, outlet cooperatively disposed to feed the suspensio of fibers to said rotating, discharge orifices. 4. Apparatus according to Claim 3 or 4 wherein said outle includes means for adjusting the width of said outlet. , · 5. Apparatus according to Claim 2 wherein 3aid outlet " 4 37203/2 6. Apparatus according to Claim 3 wherein said outlet is a uniform width slot and wherein said duot includes ' a conduit section of comparatively large cross-sectional area and a tapering throat communicating said conduit with said slot. 7. Apparatus according to Claim ·€ wherein said slot is deeper at its upstream end than at its downstream end and wherein the root of said slot follows a curve from said upstream end to said downstream end, 8. Apparatus according to Claim 7 wherein said curve is a continuous curve. • 9. Apparatus according to Claim 3 wherein said Bupply means further includes valve means for selectively increasing and decreasing the effective delivery area of said outlet. said fiber delivery means. any preceding 12. Apparatus according to/Claim wherein said- fiber delivery means includes a plurality of curved vanes defining, said discharge orifices therebetween, said vanes directing the suspension of fibers radially outwardly of the center of rotation of said discharge orifices; and wherein said drive 1 · Apparatus according to any preceding claim wherein said drive means is a variable speed drive means for varying the angle of discharge of the suspension of fibers* 14· Apparatus for producing a non-woven fibrous element substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings*