US3867749A

US3867749A - Press device for pressing liquid from a fibrous body

Info

Publication number: US3867749A
Application number: US416915A
Authority: US
Inventors: Erich Betz
Original assignee: DLW AG
Current assignee: DLW AG
Priority date: 1971-11-01
Filing date: 1973-11-19
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25

Abstract

Apparatus for pressing liquid from a fibrous body, particularly a loose one such as paper in process of fabrication. A first drum of rigid material, particularly metal, cooperates with a second drum which has a resilient envelope and wrapped wire around the envelope. The wrapped wire consists of predrawn synthetic material, for example polyamide, wound at distances smaller than the diameter of the wire.

Description

United States Patent 1191 1111 3,867,749 Betz Feb. 25, 1975 PRESS DEVICE FOR PRESSING LIQUID 1,175,940 3/1916 Farnsworth et a]. 162/372 FROM A FIBROUS BODY 3,349,693 10/1967 Mitchell 29/130 X [75] Inventor: Erich Betz, Worms, Germany FOREIGN EN S 0R APPLICATIONS A gneez Bletlghelm/wurtt" Germany 1,109,902 4/1968 Great Britain 29/130 [22] Filed: 7 Nov. 19, 1973 Primary Examiner-Alfred R. Guest [21] Appl' 416815 Attorney, Agent, or Firm-Nolte and Nolte Related U.S. Application Data [63] Continuation of Ser. No. 197,846, Nov. 1, 1971, [57] ABSTRACT abandoned. I

. Apparatus for pressing liquid from a fibrous body, par- [52] us. Cl l l 2'9/121 R ticularly a loose one such as paper in process of fabri- [51] 1.... c1..11111111.11111111111 1.1:111111....:..1.111 m, 27/02 A drum of rigid material, particularly of Search H R metal, cooperates With a second drum which has a 1'6- silient envelope and wrapped wire around the envelope. The wrapped wire consists of predrawn synthetic [56] References Cited material, for example polyamide, wound at distances UNITED STATES PATENTS smaller than the diameter of the wire.

1,123,388 1/1915 Schaanning 29/121 H 6 Claims, 2 Drawing Figures PATENIEB FEBZ 51975 INVENTOR fP/(Y/ 55 PRESS DEVICE FOR PRESSING LIQUID FROM A FIBROUS BODY This is a continuation of application Ser. No. 197,846 filed Nov. 11, 1971 now abandoned.

BACKGROUND AND NATURE OF THE INVENTION:

Former press drum envelopes were held by closely wrapped wires of metal but these were found unsuitable when high pressures were used between the drums since the metal wires, exposed to high bending stress in operation, began all too soon to break; also the felt or other envelope material had too much wear and tear and too little service expectancy as the wires tended to shift and the envelope was heavily loaded by drum pressure. These conditions also caused impairment of the fibrous body during the pressing process (British Pat. No. 1,109,902).

Wire has also been wrapped on a solid drum at sub-.

stantial distances of the wire turns. Wire can consist of elastic material, for example rubber or the like. Because of the wide distances between the windings of the wire, the felt is under heavy load and therefore has little service expectancy. Wires of yielding materials will not sustain the applied squeezing effect (German Pat. No. 813,840).

The invention has the object to provide a press for high working pressure with maximum protection for the heavily loaded parts and minimum impairment of the fibrous body.

This is achieved according to the invention, which for this purpose uses wire of predrawn synthetic materials, such as polyamide, wrapped at distances smaller than the wire diameter.

DRAWING:

FIG. 1 is a side view of apparatus according to the invention; and

FIG. 2 is an enlarged fragmentary side view of an element which can be used in the invention.

SPECIFIC DESCRIPTION OF AN EMBODIMENT OF THE INVENTION:

The apparatus has a hard, smooth upper drum 1 of metal, stone or the like. It has a lower drum 2 comprising a hard core 3 and yieldable envelope 4 which can have suitably selected elasticity constants, for example those of soft rubber or hard rubber. Wire 5 of synthetic material is wrapped around envelope 4, at distances between the individual windings which are smaller than the diameter of the wire which is used. The wire consists of predrawn and thereby prestretched material, such as polyamide.

The fibrous body to be pressed is shown as a strip 6- and can be in humid and loose condition. It lies on a strip 7 which comprises a body of firmly coherent fibers of elastically reacting material, for example a needle felt.

DETAILS OF WRAPPING WIRE AND FELT found suitable.

The production of fine paper requires a felt weight above 2,000 grams per square meter (g/m The use of relatively thick felt reduces the discharge of water at the pressure drum during the entry of the felt into the pressure zone, particularly in the fabrication of a humid, thin, loose, large area, elongated fibrous body, such as paper and cardboard pulp. In such cases, the thicker felt is not strongly dewatered; rather the fibrous strip yields water in the pressure zone to the adjacent felt which almost completely absorbs the water and continues to carry it. In this case, the felt has the effect of a sponge-like body which absorbs liquid in the pressure zone and yields in the wringing zone, without releasing much liquid at the pressure drum.

In connection with this, the drum corrugation provided by the wire generates a kind of pumping effect within the pressure zone, and the felt picks up liquid in large amounts. This has the advantage that the return of water or other liquid to the loose fibrous body is almost entirely excluded, even in the case of high peripheral velocities of the drums.

.Upper and lower drums l and 2 can have surfaces slightly curved along the axis. For wires 5 it has been found to be advantageous to make the cross section thereof in trapezoidal form with the wide side of the trapezium near the center of the drum. This facilitates avoidance of the clogging of interstices between the wire turns, for example when treating fibrous bodies or pulps having short fibers. On the other hand, when dewatering toward the center of the drum is to be maximized, the opposite arrangement of the trapezoidal wire is to bepreferred.

As shown in FIG. 2, wire 5A can be provided with longitudinally successive uniform attenuations and concentrations, such as to provide transitions, longitudinally of the drum, across the interstices of adjacent wire turns. This expedient can provide additional dewatering along the drum. Advantageously, such wire has contours in form of wavy lines staggered relative to one another, for example as shown in FIG. 2.

Wire 5 is wrapped around envelope 4 of lower drum 2, in pretensioned condition. Particularly firm wrapping is achieved by immersing the drum, complete with wrapping, in water at to C. for several minutes. This leads to contraction of the prestressed synthetic wire material, thereby adding to the tension of the wrapping.

OPERATION, ADVANTAGES AND FURTHER DETAILS OF THE INVENTION:

The press drum construction according to the invention is particularly suitable for application of high pressures, for example up to 200 kilopounds per centimeter (kp/cm), to achieve a high degree of drying of the loose fibrous body to be dewatered. The service expectancy of wire 5 is fairly high because of its high strength and 3 its behaviour, during pressing, which resembles that of yielding envelope 4 of the drum. Similar considerations apply to supporting fibrous body 7, particularly needle felt, the wear and tear of which is less when using wire 5 of predrawn synthetic material, than when using metal wire. As the characteristics of yielding envelope 4 and of synthetic material 5 cooperate favorably, the fiber bond in fibrous body 6 is practically not disturbed during the pressing process. As distances are provided between the individual turns, the felt can dewater into these, with little bulging out, so that by means of the distances between wires, the drying of the loose fiber body is improved.

When a series of attenuations and concentrations is used, as in FIG. 2, there are formed areas of reduced pressure between wire and supporting felt, substantially parallel to the axis of the drum, whereby dewatering along the drum is facilitated.

When the envelope 4 of the drum 3 has rows of successive holes through this envelope, it has been found advantageous to provide grooves extending along the axis of the drum or spirally thereto, connecting the holes. The pressed out liquid then has only short paths to flow before it, for example by suction, reaches the interior of the drum. Thus, it becomes possible to maintain adequate flow velocities by low pressure differentials.

As already noted, the thickness of the felt or similar strip is such that the liquid issuing from the felt or other coherent fiber body ahead of drum 1 is absorbed by the strip as in a spongy body. In the absence of a dewatering effect within the pressure zone, the loose fiber body is not exposed to remoistening even in the case of high drum velocities.

WIRE CHARACTERISTICS Advantageously a wire made of nylon with a circular cross section should be used.

The diameter of the wire may be between 1,0 and 3,0 mm. depending on the nature of the material to be treated, i. e., paper or cardboard, and on the nature of the needlepunched material used.

The wire requires the following characteristics 1. Load capacity of 100 kgs at a diameter of 1,60 mm 155 kgs at a diameter of 2,00 mm 240 kgs at a diameter of 2,50 mm 340 kgs at a diameter of 3,00 mm.

2. Tear resistance of 45 to 50 kgs per mm 3. Tensile strength of to 18 percent.

4. Specific weight of approx. l,l4 g per cm The pretension of the wire ranges from 50 to kgs at a diameter of 2 mm, and from to kgs at a diameter of 3 mm. The wire is pretensioned by means of a specially developped arresting and stretching gear with measuring device. From here the wire is wrapped around the corresponding drum.

What is claimed is:

1. in a press drum having a wrapping for use in the process of dewatering a loose wet fibrous body such as wet paper pulp, the improvement comprising:

a. an envelope of yieldable material to cover said drum, and

b. a linear wire wrapped about said envelope, said wire consisting of predrawn synthetic material having a linear body alternately provided in sequence with attenuations and concentrations along said bodys length, whereby said wire as a result of said shape induces a pumping action which improves the function of dewatering said paper pulp during processing.

2. The apparatus of claim 1 wherein the distance between adjacent sections of the synthetic wire, as wrapped around said envelope, are smaller than the diameter of said wire.

3. The apparatus of claim 1 wherein the body of the linear synthetic wire has continuously successive and substantially uniform attenuations and concentrations along its length.

4. The apparatus of claim 1 wherein the exterior of the body of said synthetic wire is provided with a profile in the form of wave lines staggered relative to one another.

5. The apparatus of claim 1 wherein the wire is alternately provided with a trapezoidal cross-section.

6. In a press drum having a wrapping for use in the process of dewatering a loose wet fibrous body such as wet paper pulp, the improvement comprising, an envelope of yieldable material to cover said drum, linear wire means wrapped around said envelope, said wire means consisting of predrawn synthetic material having a linear elastic body, adjacent turns of which are spaced one from another a distance which is smaller than the width of said wire, said wire thereby comprising means for inducing a pumping action which improves the function of dewatering the paper pulp during processing the spaces between the turns providing means for passing water to and from said envelope.

Claims

1. In a press drum having a wrapping for use in the process of dewatering a loose wet fibrous body such as wet paper pulp, the improvement comprising: a. an envelope of yieldable material to cover said drum, and b. a linear wire wrapped about said envelope, said wire consisting of predrawn synthetic material having a linear body alternately provided in sequence with attenuations and concentrations along said body''s length, whereby said wire as a result of said shape induces a pumping action which improves the function of dewatering said paper pulp during processing.