FI57625C - CYLINDERSIKT FOER KONTINUERLIGA RUNDSIKTMASKINER FOER TILLVERKNING AV PAPPER PAPP OVAEVDA TYGER FIBERCEMENTAEMNEN OSV - Google Patents

Description

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Patent- och registerstyrelMn '7 Anafiktn Utta | d odi utl.ikrlften publtc «nd 30.05.80 (32) (33) (31) Pyydttty« tuolkeui - Begird prlorlttt 18.02.69

Italy-Italy (IT) 35081+ A / 69 (71) Fibrostampa Srl, Via Andrea Doria 10, Milan, Italy-Italy (IT) (72) Armando Frezzotti, Fabriano (Ancona), Italy-Italy (IT) (7I * ) Oy Kolster Ab (5I +) Drum screen and imaging for other cylindrical screen machines for the production of paper, cardboard, non-woven fabrics, fiber cement waves, etc. - Cylindersikt för kontinuerliga rundsiktmaskiner för tillverkning av papper, Papp, ovävda Tyger

The invention relates to a drum screen for continuous cylindrical screening machines for the production of paper, cardboard, weaving tower fabrics, fiber cement materials and the like.

Continuous cylindrical strainers for papermaking are known to have one or more boxes with a tray containing aqueous fibrous slurry and a hollow cylinder rotating about a horizontal axis, surrounded by a metal screen or the like, which partially sinks into the material in the tray. As the water in the trough penetrates through the eyes of the screen, the fibers settle on the outside of the cylinder and form a thin layer of fibers. This fibrous layer rising from the porridge settles tangentially on the lower surface of the receiving felt passing through the drum screen and pressed against the felt roll. In machines with more than one box, successive layers of paper are created, which are superimposed on the receiving felt to form the desired thickness.

2 57625

In order to achieve in such machines that the sheet adheres to the lower surface of the receiving felt, it is necessary that there are no interruptions in the sheet, especially in the transverse direction of the cylinder.

The object of the invention is to provide a crumb screen with which a "cut-out" endless paper layer can be produced according to characters, patterns or drawings of the desired quality. This cut-out layer can be embedded between two continuous layers of the same or different color to obtain a watermark paper, which may have a color different from the color of the sheet, or it can be placed alone or together with other cut-out layers as a continuous layer to form the desired pattern or characters one by one. or of multi-colored paper or paperboard.

According to the invention, a drum screen is proposed, which screen consists of a rotatably mounted shaft to which two wheels are fixed at regular intervals, each of which is surrounded by a circumference with radial openings, which circumferences support adjacent box-shaped suction cells surrounded by a stable fabric, in which case reversible distribution devices divided into radial canisters, which are in close sliding contact with the inner edges of the frames and whose chambers independently comprise each other their connection to a compressed air source or a vacuum source, respectively, are arranged on one or the end surface of the column. This drum screen is characterized in that each wheel comprises at least one sector of metal that can be pushed radially against the axle to facilitate attachment and detachment of the fabric.

The invention will be explained in more detail below, with reference to the drawing, on the basis of a preferred embodiment.

Fig. 1 is a front view of the drum screen shown in partial section, Fig. 2 illustrates the drum screen in section along a plane passing through its axis of rotation, Fig. 3 shows in detail the removable part of the drum screen circumference, Figs. 4 and 5 are sections along lines A-A or B-B in Fig. 3.

Referring to Figures 1 and 2, the number 1 denotes a horizontal drum screen axis rotatably mounted on bearings, not shown, which is operated by means of an arbitrary drive or by means of a receiving felt itself. Shaft 1 is located in a tray of material containing an aqueous fibrous slurry, the aqueous fibrous slurry extending in this tray outside the drum screen of FIG. 1 to the height indicated by the number 2 and inside the drum screen to the height indicated by the number 2 '.

3,57625

The axle 1 is wedged with two identical wheels 3 at a corresponding mutual distance, around the circles of which are fixed circular circumferences 5 with screws 4, which are provided with a row of radial openings 6 and are rigidly connected to front rings 7 with a projecting edge 8.

Attached to the frames 5 by screws 11 are boxes 9 of trapezoidal cross-section, which are arranged according to the base line of the drum screen. The boxes 9 are side by side (see also Fig. 5) and have two side walls 12, a base 13 and transverse dampers 14, the shape of which is slightly curved. Outwardly, the boxes 9 are open and a screen 15 made of metal cloth or the like is tensioned over them. Each divider 16 is supported by a pivot lever 17 which is mounted by means of a hub 18 so as to rotate freely about an axis 1, the coil springs 19 arranged in the guide sleeve 20 corresponding to the divider against the edge of the perforated circumference 5.

The dividers 16 comprise segments 21 with seals 22 between which are radial chambers 23 which communicate with the openings 6 of the circumference 5 and thus through the openings 35 to the interior of the boxes 9. The radial chambers 23 of the manifold 16 have a connection 24 for connection to a source of compressed air or a source of vacuum.

An endless receiving felt 25 slides tangentially over the metal fabric 15 and is pressed against the drum screen by the felt roll 26.

To facilitate the insertion and removal of the metal fabric 15, the wheels 3 have a cut 27 which can be pushed towards the center of the drum screen by means of a threaded sleeve 28 acting on the pin 29. To enable this pushing, the boxes 9 for this sector are surrounded by lateral pins 30 (see Figures 3 and 4) with tongues 31 aligned with the transverse dampers 14.

The pins 30 are fixed to plates 32 provided with fixing screws 33. As can be seen in Fig. 4, the pins 30 for the part of the circumference 5 are immediately screwed into the handle.

The mode of action of the described drum screen is as follows.

Assuming that the arrows in Fig. 1 indicate movement, those chambers 23 of the divider 16 between the submerged zone of the drum and the point of contact of the felt roll 26 and felt 25 come under reduced pressure, while other chambers 23 in the direction of movement after this point of contact are supplied with compressed air. It follows that the fibers contained in the aqueous slurry 2 adhere to the metal fabric 15 under the felt roll 26, while after this point the sheet formed by these fibers is pressed against the lower surface of the receiving felt by compressed air, from which it is removed for further processing.

If the metal cloth 15 is rendered impermeable by varnish or other suitable procedure to one or more zones of 57625 shaped according to arbitrary marks or letters, then no sheet is formed in these zones, so that a continuous sheet cut from said zones is obtained. the effect coming from the chamber 23 from the circumferential openings 6 into the interior of the boxes 9 as soon as they move past the divider 16. In order to regulate the negative pressure and the overpressure in the distributor 16, it can be turned around the shaft 1 manually or by means of an arbitrary control, not shown.

Water jets coming from the nozzles 34 have been set up to remove any fibers adhering to the areas covered by the metal cloth 15.

The described drum screen allows much higher speeds to be achieved than hitherto known drums.

With power boxes, which in themselves already allow for high speeds, these speeds can apparently be doubled, resulting in always well-padded sheets. Furthermore, much larger sheet thicknesses can be achieved compared to a conventional drum, so that the drum screen according to the invention is particularly suitable for cylindrical screen machines for producing cardboard and paperboard.

With the quality described with several drums or with one normal drum and several drums of the described quality used in a cylindrical sieve machine for making paper, innumerable special paper grades which cannot be obtained with known machines can be realized.

A cylindrical strainer with two drawers, the first box of which is fitted with a normal drum screen and the second box fitted with a drum screen with suction and blow boxes, can be made of special connecting paper because the first, normal or special drum screen forming the finished sheet roll letters or drawings obtained as positive or negative on the metal fabric of the special column can be printed on this sheet during the joining step.

If the cut sheet produced by the special drum has a different color than the sheet formed by the first drum, then after merging a single sheet of paper is obtained, each side of a different color, but giving the letters, numbers or drawings on the metal cloth of the second drum screen in a single color.

With one normal machine and one drum screen according to the invention, it is possible to produce continuously uncut envelopes already provided with a second color lining, whereby tear yarns are placed on the first sheet delimiting the shape of the shell and the shape of the lining is implemented in a positive sense so that both drums synchronous with the exact position in which the liner must be placed in the envelope.

s 57625

A machine with three drawers, the first and third with normal drum screens and the second with a suction and blow drum in the middle, with the middle rurrrum producing drawings in a different color than the drums of the other two sheets, can be combined to form a single sheet with different internal letters. and drawings. These papers are very useful for security purposes and are commonly used in securities.

If in said machine a metal fabric for making a watermark is perforated and the perforated part is limited by varnish, a sheet of paper is provided after joining the sheets, which is provided with a watermark on the inside, which may be a different color from the other sheet.

This was previously only achievable by hand, while the present term allows this work to be done primarily by hand continuously and industrially.

If, instead of only one suction-blowing column, said machine is provided with two rollers in the second and third boxes, both of which are synchronized, a varnish-limited perforation can be placed in the other, while in the third hold the part perforated in the second part can be varnished, that after the sheets are joined, a sheet of paper is obtained which, when three substances of different colors are used, has a single color on one side and a second color on the other side and a third color is given by a watermark which synchronized with the empty space in the third drum screen.

If the machine were equipped with three suction blowing drums, in which both lateral suction drums produce empty zones at equal points, then a single watermark sheet would be obtained, whereby the corresponding color of the substances may have a different color on the watermark sheet.

Finally, it is possible to make use of the principle of a continuous machine already described, which is equipped with as many boxes as possible to reproduce colors, so that the first sheet formed by a normal drum screen also merges with parts of different appropriately selected colors to reproduce arbitrary drawing with different colors.

The invention has been described in terms of a preferred embodiment, however, it is clear that numerous practical embodiments are possible within the scope of the invention.

Claims (4)

6 57625 A drum screen for cylindrical screen machines for making paper, cardboard, etc., which screen consists of a rotating bearing shaft (1) to which two wheels (3) are fixed at regular intervals, each of which is surrounded by a circumference (5) provided with radial cars (6), the circumferences support adjacent plate-shaped suction cells (9) arranged along the base line of the rupture, the outwardly facing open surface of which is surrounded by a metal fabric (15), whereby reversible dividers (16) divided into radial combs (23) are arranged on one or both end surfaces of the rum, (5) in close sliding contact with the inner edges and whose chambers each independently comprise their own connection to a connecting pipe to a compressed air source or a vacuum source respectively according to the position of the extension device (16), characterized in that each wheel (3) comprises at least one radially against the shaft (1) tucked in a sector (27) to facilitate attachment and detachment of the metal fabric (15). Drum screen according to Claim 1, characterized in that the radii of the sector (27) for full displacement are a threaded sleeve (28) screwed onto two coaxial threaded pins (29). Drum screen according to Claim 1, characterized in that the cells (9) corresponding to the movable sector (27) are connected to other boxes by longitudinal strips (32) which are provided with seals and fastened with screws (33). Drum screen according to Claim 3, characterized in that the longitudinal connecting strips (32) connecting the cells (9) corresponding to the sector (27) to the other boxes have a row of pins (30) with tongues (31) at the free ends aligned with the transverse plates ( 14).