FI57280C - BAOGFORMIGT FOLIEBLAD FOER MASKINVIROR VID PAPPERSMASKINER - Google Patents

Description

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JfiPV IBJ (11) utlAggninosskmft 57280 C (45) .7 ":: .. 'ty η Γ.7 19" -', ^ ^ (51) Kv.ik. * / Int.a. · D 21 I 1 / 00 FINLAND —FINLAND (21) l ^ t ^ l »kMMM-Pat« MMMBkning 16/70 (22) Hak «mlipUvi — Anaeknlngidag 05.01.70 * F 1 * (23) Alkupllvf — GIM | hMid« g 05.01.70 ( 41) Tullut (ulkMal - Blivtt offancllf 30.07.70

Patents- rakirari curb .... __.

_. . ,,. (44) Date of commencement of production at the month of commencement.

Patent- och registerstyrelaen Araeion utbed och uti.skriftan pubUcarad 31.03.80 (32) (33) (31) Pyri · ** / «tuolkuu * —Bogird prloritut 29.01.69

Italy-Italy (IT) 6050U A / 69 (71) (72) Glauco Corbellini, Via Del Bon, 6l, Udine, Italy-Italy (lT) (7 ^) Leitzinger Qy (5k) Curved blade for paper machine wires - Bägformigt folieblad This invention relates to a curved blade for machine wires of paper making machines.

It is known to provide a device for paper machines, called a machine wire, comprising a loop-like fabric belt rotating around rollers, whereby a wood pulp mixed with water is placed on said machine wire from a main box. Water seeps under the machine wire as the latter moves on its support rollers so that the wood pulp leaves the machine wire only in a moist state and ready for papermaking.

In order to reduce the manufacturing costs, attempts have been made to increase the speed of the machine wire more and more, which, however, results in a shorter residence time of the wood pulp on said machine wire, which makes it very difficult to remove as much water as possible from the pulp.

To solve this problem, i.e. In order to increase the speed of the machine wire and at the same time remove as much water as possible from the pulp fed to the wire, elongate blades have previously been shown below the machine wire. and while the latter moves rapidly, they create a vacuum below the machine wire, promoting the removal of water from the pulp to provide good quality paper.

However, these known blades have significant defects because such blades, made of soft materials, wear out quickly and need to be replaced from time to time. Attempts have been made to make the blades of very hard materials, such as ceramics and carbides, but it has been found that materials which cannot be machined into large blades with a very flat, smooth free edge intended against the surface of the machine wire, their fractures and due to their hardness would cause rapid wear of the machine wire, which should therefore be renewed from time to time. In this context, it should be noted that the price of machine wire is very high and its replacement would lead to the shutdown of the entire papermaking machinery and would cause very significant financial losses.

Therefore, the above-mentioned blades must be made of materials which are hard, i.e. resistant to wear, but which have a very low coefficient of friction and which are able to withstand the corrosive effect of liquids to be dried through the machine wires of papermaking machines. As in the case mentioned above, the production of curved leaf blades from these materials is very difficult and expensive, because hitherto efforts have been made to make blades with a substantial cross-section to ensure considerable mechanical bending and torsional strength.

The object of the present invention is to overcome the above-mentioned defects, and in particular to provide a curved leaf blade which is relatively inexpensive and made of a non-wearable hard metal alloy which cannot be affected by chemical substances and which has a low coefficient of friction.

Another object is to provide a blade which can be manufactured in a relatively simple manner, the free edge of which is intended to wipe the underside of the machine wires in papermaking machines, whereby this edge is completely straight and smooth.

It is a further object to provide a lighter blade which can be mounted below the machine wire in a bearing which, by simple turning, allows the clearances created by wear between the blade and the machine wire to be removed during operation of the papermaking machine.

These objects of the invention are achieved by a leaf blade, which according to the invention is characterized in that a plastic plate is attached to the upper surface of the body, forming a smooth, planar upper surface together with a hard metal cast blade strip having a blade strip composition of: about 2% C, about 35% Cr, about 18% W and about 45% Co.

In order that the blade structure and characteristics may be more clearly understood, one embodiment thereof will be described with reference to the accompanying drawings, in which:

Fig. 1 is a schematic longitudinal view, and shows a part of the machine wire and a cross-sectional view showing four curved leaf blades placed below said machine wire.

Figure 2 is a perspective and partially sectioned view of the steel.

Figure 3 is a cross-sectional view of said steel taken along line III-III of Figure 2.

Figure 1 shows part of a paper manufacturing machine the machine wire 1, wherein the machine wire moves in the arrow F direction, and on which a known type of headbox (not shown) is dropped puupaperimassan 2. The curves Journal of blades 3 is provided with a machine wire below 1 and have a longitudinal edge of the wiping plane of the wire 1 the underside, wherein these the blades 3 extend transversely across the machine wire 1 and have a longitudinal tail groove which allows the blades to be mounted on the shaped surface of a rigid beam 4 pivotally mounted on a pin 5 supported on a machine body (also not shown in the drawings for simplicity).

During the operation of the papermaking machine, the machine wire 1 moves in contact with the free edges of the blades 3, where a vacuum is formed, which promotes the exit of the pulp 2 and water A through the machine wire 1. As the machine line moves to the right, the water content of the pulp 2 decreases evenly and the thickness of the pulp on the wire also decreases.

When the play is created by wear between the free edges of the blades 3 and the underside of the machine wire, it is sufficient to turn the beams counterclockwise in their pins 5 to eliminate such shortening; of course, this only applies within certain limits that can be easily determined experimentally.

In particular, Figures 2 and 3 show the structure of blades 3 comprising an elongate low friction strip 6 which is not corroded by chemical substances and which is made of a wear-free hard alloy, this strip 6 being attached to a first elongate body 7 made of moldable material and reinforced a longitudinal metal insert 8 with holes 9 to ensure good attachment of the insert 8 to the material body 7 to be formed.

The lower part of said first body 7 has a longitudinal groove, the inclined edges 10 of which give a dovetail shape to said groove and allow the blade to be mounted simply by sliding one of the previously described beams M · into a dovetail cross-sectional part.

A second elongate body 11 made of a non-wearing mouldable material is also attached to said body 7, the free surfaces of the body 11 and the strip 6 forming a substantially flat surface against the machine wire 1 when the latter is in operation.

In addition to the metallic telegram 8, the first body is also preferably reinforced with a glass fiber evenly distributed in the mouldable material forming said body 7.

The elongate strip 6 is made of a mixture of carbon, chromium, tungsten and cobalt, possibly comprising a small amount of iron, manganese, silicone and nickel, in particular it has been found that a mixture comprising 2% carbon, 35% chromium, 18% tungsten and cobalt and iron -, manganese, silicone and nickel additions for balance, perfectly suited for the desired purpose. It should be noted that the presence of iron, manganese, silicone and nickel in the mixture is not essential.

As can be seen, the transverse dimensions of the longitudinal metal strip 6 are somewhat reduced with respect to the entire blade 3, allowing said strip to be given a hdkrt shape, its free edge being projecting from the edge of the body 7 and contacting substantially directly with the machine wire 1; this would be impossible or rather difficult to achieve if the blade 3 were made of the same alloy as the strip 6, since the blade can only be made by casting and would bend considerably during cooling. The mechanical operations which would then be required to make the free edge of the blade fairly straight and smooth, which edge is intended against the machine wire 1, would be very difficult due to the cross-sectional dimensions and the amount of deformation of the blade.

The mechanical operations required, on the other hand, to make the free edge of the strip 6 smooth and quite straight after it has been formed are, on the other hand, relatively simple, as mentioned above.

To obtain the blade according to Figures 2 and 3, a base plate with a recess shaped in the same way as the blade to be received has been used. The elongate metal strip 6 and the metal insert 8 are first placed in the recess of the base plate and then a non-wearing, moldable material is molded to form the body. After the body 11 has hardened, the molding material intended to form the body 7 is cast in the recess of the base plate. The moldable materials forming the bodies 7 and 11 are inserted into the recess of the base plate in a liquid state and harden by bonding tightly to each other and to the strip 6.

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