US2711675A - Machine for the manufacture of felted sheet material - Google Patents

Description

June 28, 1955l H. M. BROWN MACHINE FOR THE MANUFACTURE OF' FELTED SHEET MATRIL.

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ATTORNEYS UnitedStates Patent() 1 2,711,675 MACHINE FOR THE MANUFACTURE F FELTED SHEET MATERIAL Howard M. Brown, Wood-Ridge, N. J. Application December 21, 1951, Serial No. 262,777

1 Claim. (Cl. 92-38) i This invention relates to the manufacture of felted or paper-like products such as asbestos-cement or (by subsequent impregnation) asphalt shingle board, or paper, and more particularly to a formation unit in a wet machine ,for such manufacture, in which a layer of pulp or fiber (which may bear other solids) is deposited in a continuous layer on a moving carrier apron which forms partof the boundary to a closed vessel through which a slurry of pulp is passed under pressure,

In the formation unit of the present invention the formation cylinders of the prior art are eliminated. The slurry instead of being -lifted from a vat by a cylinder for transfer to a felting apron is deposited directlyon the apron as the latter is moved past an opening in the wall of a closed vessel filled with the slurry. Infraatmospheric pressure is applied to the exterior of the feltingapron as it passes the opening, effecting immediate extraction of water from thedeposit, and permitting the formation of a heavy sheet at a single pass. Whereas the apron is maintained in frictional contact with the walls of the vessel about most of the edge of the orifice,

a clearance is provided between the apron and the vessel` at the limit of the opening in the direction of motion of the apron, so that the adherent layer of pulp, ber, or cement-fiber mixture is not removed. The formation unit of the present invention therefore permits the formation of a heavy sheet at a single pass of the felting apron past the reservoir of slurry. It further eliminates entirely the formation cylinder or cylinders with their maintenance and the dilution of the slurry in the reservoir commonly occurring in cylinder type machines of the prior art due to the rinsing water applied to the exterior of the cylinders. The invention has application to the manufacture of a wide variety of felted products such a's paper, and especially to the manufacture of roofing materials such as asbestos-cement shingles and the fibrous felted web of asphalt-impregnated shingles.

The invention will now be described in further detailv Fig. 2 is a sectional view taken'on the line 2-2 of Y Fig. 1;

Fig. 3 is a fragmentary sectional view taken along the line 3-3 of Fig. l;

Fig. 4 is an enlarged sectional view similar to a portion of Fig. l, illustrating the closure of the formation aperture in the slurry chamber at the rear thereof; and

Fig. 5 is a sectional View in plan taken on the line 5 5 of Fig. l.

In Fig. 1 a formation unit generally indicated at the dashed line box 3 provides means by which a layer of fibrous material is transferred from a slurry to an endless felting apron 5. The apron with its adherent layer or web of fibrous material is passed from the formation unit about suitable carrier rolls 7 and 9` to an accumulator roll 13 to which it is transferred fromv the carrier apron. The web accumulateson the roll 13 in one or more layers before being cut by a suitably arranged knife, not shown, which may or may not form part of the roll, and is then transferred to a delivery belt 15 for transmission to subsequent stations where operations such as compacting and drying may be performed. The accumulator roll is 2,711,675 Patented June 28, 1955 supported in position to be loaded against a driving roll 14, which, like the tail roll 7 of large diameter, may be rubber covered.

The apron moves from the driving roll 14 past idler rolls 83, a shower 80, a beater or whipper 81, to a water extractor, and thence about further positioning rolls '84' which present it anew to the formation unit. The extractor may take the form of a suction box 82 connected wtih a suitable source of vacuum.

The formation unit includes a chamber, tank or vessel generally indicated at 17, having front and rear walls 16 and 64, top and bottom walls 18 and 20 and side walls 39 and 41 (Fig. 2). Inlet and outlet conduits or passages 19 and 21 permit the circulation of a slurry through the tank. The tank further includes an opening at 23, better sheen in Fig. 5, past which the apron is drawn and at which the actual formation of the web or sheet takes place. Of course the formation vessel may vary widely in shape from that shown in the drawings. Provision for a continuous and controllable through-flow of slurry and of a suitable formation aperture as hereinafter described are its most important features. The formation aperture is preferably of substantially rectangular shape, and of the width (transversely of the apron) of the web to be formed. ln a 'preferred embodiment the effective shape of the opening is determined by movable sealing members' mounted on the formation vessel in position to cooperateY with a suction box supported adjacent the opening and against which the felting apron rests in closing the opening.

A slurry of suitable composition for formation of the desired sheet is pumped continuously through the chan1 ber 17 by means of pumps 25 and 27 which communicate with a storage system, not shown. For example in the manufacture of asbestos-cement board, a mixture of solids consisting of some 12 per cent asbestos fiber, l0 per cent cement dust and 78 per cent cement is mixed with water until the solids amount to some l5 per cent` to 35 per cent of the total. Or, for the manufacture of the board used in making asphalt-impregnated roofing shingles, solids consisting of 80 per cent wood fiber, 15

per cent waste paper and5 percent wool clippings are mixed with water to form the slurry, The iiow of slurry through the chamber 17 may be controlled by means of a valve 29 in an exit passage 31 communicating with the exit conduit 21. In the embodiment shown the exit passage is formed by the rear wall 64 and a baie 37 presently to be described. The valve may however be placed in the exit conduit 21 instead. Agitators 33 and 35 suitably drivenv maintain the slurry in a state of uniform suspension at both inlet and outlet ends of the chamber.

The chamber may advantageously be provided with a bafile or flow deck 37. The deck extends across the width of the chamber between side walls 39 and 41 and compels the slurry to flow an extended path about an exten# sion 38 of the chamber and thence to stream past the formation opening 23 in the general direction of motion of the apron 5 which is from right to left in Fig. l of the drawings. A high streaming velocity for the slurry is not necessary however, nor need any particular relation be achieved between the streaming velocity and the speed of the apron. Rather the flow deck and the extension 38-of the chamber under the top wall 1S serve to reduce the turbulence of the slurry before it is presented to the part of the chamber bounded by the felting apron at its working surface presented adjacent the opening23V and forms means to conduct the apron past the opening.

r[lle sealing boards are stressed against the apron as positioned by the suction box so as to prevent substantial loss of slurry from the chamber except in the form of a sheet deposited on the apron.

This construction is illustrated in Figs. 2 'to 5. In Fig. 2 the formation chamber is shown bounded by side walls 39 and 41 on which are mounted boards 43 and 45 resiliently stressed upward into contact with the apron 5 by springs 47 which are aixed to the` chamber and which bear on anged lower portions of the boards. The sealing boards may be made of metalor other material which withstands exposure to Water and which will not injure the felting apron. The boards 43 and 45 make a nice lit with the walls 39 and 4l and extend from the rear wall 64 to the left or rear end of the top wall 18 of the chamber. They may be retained on the side walls 39 and 41 by. means of any conventional construction such as pins 43 which t into vertical slots in the sealing boards. At the front of the opening 23, i. e. at the limit at which the apron advances over the opening, a similar board 50 is stressed as by means of a leaf spring 52 into contact with the felting apron. At the corners of the opening 23 the boards 43, 45 and 50 are shaped to lit nicely with each other and with a weir 62 presently to be described, in order to minimize loss. of slurry from the chamber by leakage.

The formation aperture 23 is limited at the departing side of the felting apron by means of a movable weir or dam 62 aixed to an end wall 64 of the chamber as shown in Fig. 3. The vertical position of the darn 62 may be nicely controlled by means of screws 66 journaled for rotation with respect to the end wall 64 and engaging nuts 68 on the darn. The upper edge of the weir is adjusted to a level below, i. e. inward or re-entrant of the chamber, with respect to the coplanar edges of the boards 43, 45 and 50. The clearance between the upper edge of the weir and the edges of the boards 43 and 45 is however small compared to the dimensions of the formation opening 23.

The position of the felting apron at thev formation opening is determined by the suction box generally indicated at 60, supported in fixed position by means not shown, against whose lower and pervious working surface the apron is held by the pressure of the slurry inside the chamber 17 as well as by the suction created within the box 60.

Accordingly the formation chamber 17 constitutes a closed vessel having over a substantially plane rectangular aperture a moving closure formed by the felting apron, with a further clearance provided between the dam 62 and the apron about the edge of the aperture at which the apron leaves the chamber.

Fig. 5 shows in plan the opening 23 and the boards 43, 45, 50 and 62 which define it.

The endless belt-shaped felting apron is advanced past the formation chamber by means of traction applied at any convenient point, for example at a drive roll 14 at the accumulator station. The slurry is circulated under pressure (usually low) through the formation chamber by means of the pump 25, and a simultaneous suction or exhaust is applied to the apron over the aperture 23 by means of the suction box 60, which connects at a conduit 6,1 to suitable air-pumping means not shown. A further conduit 63 permits removal from the suction box of Water drawn through the apron from the layer of solids disposed thereon in the formation process. By the vcombined action of the hydrostatic pressure Within the slurry in the chamber and the suction applied at the box 60, a layer of the solid components of the slurry is caused to adhere to the apron as the latter is exposed to the slurry at the opening 23.

The suction box 60 may advantageously be extended beyond the opening 23 in the direction of motion of the apron and preferably extends as shown in the drawings to the immediate vicinity of a pair of rolls 70 and (itl 72 between which the fibrous web or layer of the apron is squeezed to extract water and to improve its adherence to the apron. The roll 70, termed a couch roll in the art, is provided with a resilient surface as by a rubber covering, whereas the roll 72, termed a dandy roll, is

covered with screening or similar perforated material..

The porosity of the roll 72 and the resilience of roll 70 permit the newly formed web to be squeezed without crushing. yA shower 74 is provided within the roll 72 to clean its exterior surface of ber particles which come to adhere thereto. The water employed for rinsing the roll 72 and for cleaning the apron at the shower 80 represents the entire waste water in machines employing the formation unit of the invention. Moreover the fibrous content of such rinse water may be recovered in a separate operation.

The thickness of the sheet formed depends upon the consistency and composition of the slurry, upon the linear speed of the apron and upon the degree of vacuum applied to the suction box overlying the belt at the formation area. Suiicient clearance is left between the dam 62 and the apron to permit undisturbed passage out of the chamber of the newly formed web. In practice there will occur more or less leakage of the slurry at this clearance. This is returned to the reservoir by the pump 27, an additional wall preventing dilution thereof by the rinse water applied to the dandy roll 72.

In passage from the tail roll 7 to the collector roll, the apron with its layer of fibrous material may be subjected to a further process of water extraction at additional suction boxes such as 76.

The formation unit of the invention may advantageously be constructed to include the couch and dandy roll 70 and 72, it being advantageous to locate them as close along the carrier apron to the formation area as possible.

In the embodiment of the invention which has been described, the suction box has been shown as including movable carrier tapes to define its working surface and to prevent the collapse of the felting apron. Other types of suction box may of course be employed instead. Moreover a movable support for the suction box may be substituted for the movable sealing boards 43, 45 and 50. In such a construction the formation chamber would have the formation aperture defined by the lixed walls of the vessel itself.

I claim:

A machinek for the manufacture of a felted sheet comprising a formation chamber having front, rear, top, bottom and side walls, a slurry inlet passage, a throttled slurry outlet passage, and a substantially rectangular opening in said top wall; said chamber being closed except for said passages and opening; a suction box supported adjacent said opening; sealing members supported on said chamber about three sides of said opening; means to pass an endless belt of water-pervious fabric between said suction box and opening in contact with said sealing members; a weir adjustably mounted on said chamber along the fourth side of said opening to provide a clearance between said belt and Weir; and means to force a slurry under pressure through said chamber.

References Cited in the file of this patent UNITED STATES PATENTS Norway Feb. 17, 1941

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