FI59129C - RAFFINATORSKIVA - Google Patents

Description

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1 J 1 'UTLÄGGNI NGSSKRIFT D 7 1 * y ^ Patent meddelat ^ ^ ^ (51) Kv.lk.3 / lnt.CI.3 D 21 D 1/30 FINLAND —FINLAND (21) P »t.nttlh» k .mu.-P «.nt« »öknln, 781793 (22) Haktmliptlvl - AnaBknlngadag 06.06.78 '* (23) Alkupilvl —Glltlfh« sdtg O6.O6.78 (41) Become Public - Bllvlt offuntllg 07.12.79

Patents and registries .... ...... ...

_ '. (44) Date of publication. -

Patent and Registration Office Ansektn utlagd och uti.skrtften pubiicend 27.02.8l (32) (33) (31) Requested privilege — Begird prlorltet (71) Vsesojuznoe Nauchno-Proizvodstvennoe Obiedinenie Tselljulozno-Bumazhnoi Promys (SU) (72) Lev Nikolaevich Laptev, Leningrad, Sergei Sergeevich Legotsky, Leningrad, Vladimir Andreevich Semenovsky, Karelskaya ASSR, Kondopoga,

Sergei Sergeevich Sambursky, Tallinn, Abram Borisovich Litvinov,

The present invention relates to disc or abrasive mills, and in particular to refining discs, the use of which is particularly advantageous in the manufacture of paper.

To produce high quality paper, many different grinding mills are used to grind the cellulosic pulp. The most commonly used double disc refiners are for grinding pulp.

In known disc refiners, the key parts consist of two coaxially arranged discs, the opposite working surfaces of which grind the material passing between them. Very commonly used are double rotary refiners, the second disc of which is fixed and is called a stator, and the second disc of which is rotatably mounted and is called a rotor. Each disc, both the stator and the rotor, is formed by two parts, namely a base and a refining plate attached thereto. In most cases, the refining plate is formed as a metal disc on which the stallion is mounted with refining rods spaced apart to form channels therebetween.

The most common requirements for the refining process of cellulosic pulp used in the production of high mechanical strength paper are to produce pulp products consisting of flexible and plastic fibers with the highest possible active surface area and to minimize the risk that the fibers would be cut. In addition, the treated fibers must be fluffed, which can be achieved by subjecting the fibers to the multiple brushing effect of the refining plate.

However, it is difficult to meet the above requirements when using a refiner disc with a metal refining plate, since the latter exerts a considerable shear effect on the fibers. In this case, the fibers become cut short without brushing and cracking and do not receive the desired flexibility or plasticity. In paper made from such a fibrous product, the fibers are loosely bonded, which reduces the mechanical strength of the paper. Metallic refining sheets give a particularly detrimental effect when grinding or refining short-fiber wood chips, because cutting such fibers short reduces the mechanical strength of the paper.

Discs with a refining plate made of Sint-rolled metal are known in the art. The very fine-porous structure of the sintered metal allows the fibers to be brushed more vigorously. Because it takes a very long time to make refining plates from sintered metal, such discs are not widely used. The most common disadvantage of discs with metal refining plates is the high noise level due to the continuous interaction between the metal plates of the rotor and stator during refining time. In addition, refiners are known which are provided with two discs, namely a rotor with a metal refining plate and a ceramic stator with a working surface made of an abrasive with a better ability to brush the fibers. Because the clearance between the rotor and the stator is negligible, the discs repeatedly come into contact during refining work, resulting in rapid wear of the rotor's metal refining plate as it contacts the abrasive surface of the stator, forcing worn parts to be replaced very often.

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In addition, a refiner disc is known, the refining plate of which contains parts made of metal and ceramics (see Soviet inventor's certificate No. 502 993), which disc comprises a base carrying a combined metal-ceramic refining plate. The refining plate consists of a central metal ring equipped with refining rods and a circumferential ring made of a ceramic-based abrasive. The utility of such a disc is limited because it is difficult to produce a ceramic-based abrasive ring with a large diameter. In addition, a peripherally placed ring made of a ceramic-based abrasive prevents the passage of pulp, which reduces refinery production and at the same time increases energy costs.

Po. The main object of the invention is to develop a refiner's disc whose refining plate is designed in such a way as to ensure a high quality 'fiber product' and lower energy costs. To this end, a refiner disc is proposed comprising a base and a metallic ceramic refining plate attached thereto, in which, according to the invention, the metal-ceramic refining plate is formed by a plurality of metal parts and ceramic-based abrasive parts arranged alternately.

Po. the refining plate of the invention ensures a high quality refining of the cellulosic pulp due to its abrasive parts and allows a reduction in energy costs due to the fact that the pulp can flow more freely between the abrasive surfaces. In addition, po. the refining plate of the invention has a longer service life because the metal parts cooperating with the ceramic-based, abrasive parts of the opposite disc wear less. This is because the parts are mounted on a support base so that the work surfaces of the metal parts are exactly at the same level as the work surfaces of the ceramic-based, abrasive parts. Thus, if occasional impacts occur between opposite work surfaces of the discs, the ceramic-based, abrasive parts exert only a slight abrasive effect on the metal parts of the opposite discs, the surfaces of which parts are made of metal, which prevents bad wear of the work surfaces. In addition, po. the discs have a lower operating noise level than the known discs, whose raffinoin plate is made entirely of metal.

It is recommended to provide the work surface of the ceramic-based abrasive parts with several channels located at an angle to the corresponding radii of the disc, the angle being in the range of about 0-90 °.

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The value of the angle affects both the quality of the fiber products and the production volume of the refiner.

If the channels are placed parallel to the respective radii of the disc, i.e. at an angle equal to or close to zero, the maximum production volume of the refiner and thus the lowest possible energy costs are achieved. However, such an arrangement of channels in the ceramic-based abrasive part causes a shear effect of the edges of certain channels on the cellulosic pulp to be treated, resulting in a detrimental cutting of the fibers into short. As mentioned above, paper made from such a fibrous product has low mechanical strength.

By placing the channels perpendicular to the respective radii of the disc, on the other hand, the greatest brushing effect is achieved in their cellulosic pulp, which in turn ensures a longer length and plasticity for the fibers, which helps to obtain high-quality paper. In this case, however, the refiner consumes more energy due to its lower production volume.

Thus, the angle between the channels and the corresponding radii of the ceramic-based abrasive portion can be selected in the range of 0-90 ° depending on the desired quality and energy cost of the fiber product.

Other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings, in which: Figure 1 shows a cross-sectional view po. a refiner disc according to the invention; Figure 2 shows a refiner disc as seen from a refining plate; Fig. 3 shows an embodiment of a refined disc with channels in ceramic-based abrasive parts; and Fig. 4 shows another embodiment of a refiner disc in which the channels extend perpendicular to the radii of the disc.

The refiner disc shown in Figure 1 comprises a base which carries a refining plate 2 fixed to it by screws 3. The refining plate 2 consists of metal parts 4 and ceramic-based abrasive parts 5 arranged alternately (Figures 1-4). The metal parts 4 are provided with protruding refining bars 6 which are separated to form channels 7. The parts 5 have a metal support 8 to which a ceramic-based, abrasive layer 9 is attached, e.g. with an epoxy adhesive. The surface of the base 1 facing the affinity plate 2 is provided with threaded bores 11 for attaching a refiner disc to a support disc (not shown), 5 59129 belonging to the refiner (not shown).

Figures 3 and 4 show other embodiments of a refiner disc in which the channels 10 are located in ceramic-based abrasive parts 5.

The operation of the refiner disc forming part of the refiner is as follows. As mentioned above, the refiner includes two discs disposed inside the refiner housing, one of which is fixed and the other rotatably mounted.

It should be noted that po. the disc of the invention may be used in conjunction with both a similar disc and another disc known in the art.

The cellulosic pulp (not shown) is continuously fed between adjacent surfaces of the disc refining plates 2 and then the pulp bypasses alternately placed metal parts 4 and ceramic-based abrasive parts 5. When the cellulosic pulp is contacted with different refining surfaces of the parts 4.5, effects resulting in intense brushing of the fibers. In addition, the granules of the ceramic-constricted abrasive act as micro-knives that grind the pulp without breaking the fibers and cutting them short.