KR20080004373A - Screen manufacturing method and screen manufactured by the above method - Google Patents

Abstract

The method according to the invention is used to produce screens, in particular screens used for press screens in the manufacture of paper. In the method a plurality of screen strips 2 have a plurality of screen holes 7 and are arranged parallel to each other between the plurality of profile bars 1. The profile bars 1 are fastened in a shape-fitting manner by recesses in at least two supports 3. Since the screen strips 2 of the present invention are not flat, for example bent or folded, their stiffness is greatly increased, resulting in a more stable operation of the screen even when the material thickness d is thin.

Description

The screen manufacturing method and the screen manufactured by the above method {METHOD FOR PRODUCING SCREENS AND SCREEN PRODUCED THEREBY}

The present invention relates to a screen manufacturing method as described in the preamble of claim 1.

The screens produced by the method may be screen baskets used for treating the pulp suspension in a kind of secondary screening process, for example in pressurized screens of the pulp and paper industry. At this time, most of the non-fiber impurities are settled by the filter member due to the size of the impurities. The fibers can pass through the screen holes with the water part as completely as possible. The apparatus is also used, for example, to fractionate pulp suspensions along the length of the fiber, ie to trap part of the fiber on the screen. Another use is to allow most of the water to pass through the screen member, along with the unwanted particulates, and to entangle the fibers. Such machines are already known and are frequently used. If the screen member insert is designed in a cylindrical or conical shape, the screen member insert is called a screen basket. In order to prevent the screen hole from clogging, a cleaner which passes mostly in close contact with the screen hole is used. Screens made by the process according to the invention can also be used in fields other than the pulp and paper industry.

It can be assumed that the machines and the screens used therein are generally suitable for their purpose. However, as it is widely used throughout the industry, since the economic aspects of the above-described fractionation process are considered very important, there have been attempts to lower the price of the screen, which is always considered a consumable. These parts are often very expensive items that can be replaced at regular intervals. Therefore, special efforts of these screen manufacturers are focused on making it possible to manufacture the screen at the lowest possible cost.

As is known, there are different types of screen holes in the screen. It is generally divided into round holes and elongated holes, wherein the elongated holes take the form of extremely narrow gaps formed over the entire axial extension of the screen basket. Since the manufacturing method is adjusted to the screen hole, the manufacturing method is distinguished for perforated screen and slotted hole screen. In the case of slotted screens, modern manufacturing methods have already been invented, in which screen holes, ie gaps, are formed between the bars arranged in parallel. However, this method always involves very high costs due to the large number of bars.

DE 196 35 189 A1 discloses a method for producing a perforated screen, in particular a perforated screen with a very large number of very small screen holes, at a very low cost.

It is an object of the present invention to provide a method for producing a screen with very fine screen holes at low cost under conditions that do not degrade durability or quality.

This object is achieved through the features mentioned in the characterizing part of claim 1.

As is known, in the screen of the press fractionator a significant load is generated due to the pressure difference in the vicinity and the hydraulic impact of the screen cleaner. Nevertheless, relatively thin screen strips may be used in the case of the present invention, since the screen strips based on the present invention have sufficient rigidity to withstand the above-mentioned forces that occur during the operation of the crimping separator. The stiffness is derived from the screen strips being flat and having curved portions, or reinforced by a number of seams or reinforcements. The requirement to use a thin plate to provide very fine screen holes (eg, a hole having a diameter of 0.05 to 9.5 mm) can also be met by the present invention.

Because screen strips are narrower than complete screen lamination and can be easily machined in relatively small machines, it is easier to perform boring, drilling or electron-beam drilling than the screen lamination. High automation rates are possible in the manufacture and assembly of parts. In many cases the screen strips have a profile bar, and therefore have a thinner wall thickness than the porous screen or screen basket, which is formed into one piece. It is also important to have different sizes of flat screens or screen baskets depending on the requirements and scale of the actual throughput. Different sizes of screen baskets produced according to the prior art require expensive large fabrication equipment, while the method according to the invention allows screen baskets of different diameters and heights to be produced in the same facility. The same applies to the case of flat screens of different sizes.

When a screen basket or screen tray is manufactured using the method according to the present invention, a structure consisting of a plurality of screen strips has a problem of warpage of a large screen thin film that may interfere with producing the screen basket sufficiently precisely. Is avoided.

The following describes the advantages of the present invention with reference to the drawings:

1 is a part of a screen made according to the invention;

2 to 5 are respective variants with different screen strips;

6 is a profile of one profile bar.

Figure 1 shows the parts already assembled after the preliminary forming step, which is the most important for producing the screen according to the invention. It can be seen here that the screen strip 2 (material thickness d: about 1 mm to 5 mm) has already been provided with a number of screen holes 7 which already comprise a cylindrical bore. The bore may have a diameter of 0.05 to 5 mm. When the screen is used for filtering the fiber suspension, a diameter of 0.05 to 0.5 mm is particularly advantageous. Or other hole shapes may be contemplated. On the longitudinal side 4 of the screen strip 2 (material thickness d: about 1 mm to 5 mm), a molding surface 5 is formed over the longitudinal extension of the screen strip. The profile bar 1 has grooves 8 opposite to each other, which grooves complementarily correspond to the forming surface 5 of the screen strip 2 described above. In this way a type coupling between the screen strip and the profile bar is possible. The profile bar 1 has a joining contour 10 (shown at the bottom in this figure) and has a projection 11 at the opposite side of the joining contour 10 (shown at the top in this figure), ie the head face. Have The support 3, which is only partially shown, has a plurality of recesses 6 open upwards, which are provided at random intervals a from each other. In the recesses 6 a profile bar 1 is fixed using its engaging contour 10. The spacing a and the width b of the screen strip 2 are chosen such that a tight coupling is made between the screen strip and the profile bar.

Preferably the method according to the invention is used to produce a cylindrical screen basket in which the support 3 is deformed into a closed ring or ring segment. Of course, the curve of this support 3 is not shown in FIG. 1.

The part shown in FIG. 1 of the screen made in accordance with the invention is used such that the inlet side is located at the top in the structure shown in the figure, for example. In this case, on the supply side, as the screen cleaner moves along the screen closely to the screen, the screen is cleaned by a hydraulic shock. The moving direction of the screen cleaner is indicated by an arrow (R). The screen strip (2) is curved and the bending axis extends parallel to the profile bar (1). As a result of this bending, a maximum height h is formed which differs from the height of the -virtual- smoothed state of the screen strip. The height h may, for example, amount to 10%, preferably 20 to 50% of the spacing a. Similar to the case of the arch bridge, the screen strip absorbs the force due to the pressure pulses caused by the cleaner and the pressure difference near the screen. In this regard, since the profile bar 1 can be formed more rigidly than the screen strip and is fixed to the support 3, the profile bar 1 can also contribute significantly to the stability of the screen. The shape shown in FIG. 1 is only one of several possible examples. For example, FIG. 2 shows a curved screen strip 2 installed completely opposite to that of FIG. 1.

In another embodiment shown in FIGS. 3 and 4, the screen strip 2 ′ has a fold or fold, where the screen holes are not shown. A double folded implementation can also be considered, according to FIG. 5, which is also only one example. In the selection of these solutions it is for example considered what form can be effective for cleaning the screen.

In many cases it has been found to be advantageous for the upper face (head face) of the profile bar 1 to have an inclination towards the cleaner side, with the inclination being for example 3 ° to 30 with respect to the upper face 12 of the support 3. An angle α is formed (see FIG. 6). 2-4 show a profile bar 1 ′ having a head face parallel to the top face 12.

1 is a portion of a screen made in accordance with the present invention.

2 to 5 are respective variants with different screen strips.

6 is a profile of one profile bar.

* Description of the major symbols in the drawings *

1, 1 ': profile bar

2, 2 ': screen strip

3: support

4: longitudinal side

5. 5 ': forming surface

6: recess

7: screen hole

8: home

10: combine configuration

11: protrusion

12: upper surface of the support

Claims (21)

Method for producing a screen comprising a plurality of screen holes (7) Manufacturing a screen strip (2, 2 ') comprising said screen holes (7) and having a molding surface (5, 5') on its longitudinal side (4), Providing recesses 6 in at least two supports 3 at a distance a on one side of the support, Facing both sides at least partially corresponding to the grooves of the forming surfaces 5, 5 ′ of the screen strip 2, 2 ′, complementarily corresponding to the recesses 6 of the support 3. Manufacturing a profile bar (1, 1 ') having a profile provided on one side (bottom side) with a joining contour (10) comprising a viewing groove (8), Inserting the profile bars 1, 1 ′ in parallel with one another in the recesses 6 of the support 3, Deforming the support 3 to form the final shape of the support, by which the profile bars 1, 1 ′ inserted in a shape-fitting manner are tightened, Method for producing a screen, characterized in that the screen strips (2, 2 ') are not flat. The method of claim 1, The recesses 6 provided on the support 3 have all the same spacing a from each other, and the screen strips 2, 2 'have the same width b. . The method of claim 2, Method for producing a screen, characterized in that the spacing (a) between adjacent recesses (6) is 20 mm to 100 mm, preferably 30 to 60 mm. The method according to any one of claims 1 to 3, Forming surfaces (5, 5 ') of the screen strips (2, 2') are the same over the longitudinal extension of the screen strips. The method according to any one of claims 1 to 4, The forming surface (5) of the screen strip (2) is formed as a protrusion, and the profile bar (1) has a groove (8) complementary to the forming surface. The method according to any one of claims 1 to 5, A curved screen strip (2) having a bending axis parallel to the profile bar (1, 1 ') is inserted. The method according to any one of claims 1 to 5, A folded screen strip (2 ') having at least one fold aligned parallel to the profile bar (1, 1') is inserted. The method according to any one of claims 1 to 7, Said screen holes (7) are holes having a diameter of 0.05 to 5 mm, preferably 0.05 to 0.5 mm. The method according to any one of claims 1 to 8, A screen manufacturing method, characterized in that the screen strips (2, 2 ') each comprise at least five rows of screen holes (7) when viewed in their transverse direction. The method according to any one of claims 1 to 9, Screen strips (2, 2 ') having a material thickness (d) of 1 mm to 5 mm, preferably 1 mm to 3 mm are used. The method according to any one of claims 1 to 10, The maximum free height h of the screen strips 2, 2 ′ is 10%, preferably 20-50%, of the spacing a of the profile bars 1, 1 ′. Clean manufacturing method. The method according to any one of claims 1 to 11, Method according to claim 1, characterized in that the profile bars (1, 1 ') have a protrusion (11) projecting above the groove (8) on the opposite side (head surface) of the engagement contour (10). The method of claim 12, The protrusion 11 has an inclined portion toward the cleaner side, wherein the inclined portion forms an angle α of 3 ° to 30 ° with respect to the upper surface 12 of the support 3. . The method according to any one of claims 1 to 13, And the support (3) is bent in the form of a ring segment by plastic deformation. The method according to any one of claims 1 to 13, The support (3) is a screen manufacturing method, characterized in that bent in the form of a closed ring by plastic deformation. The method according to claim 14 or 15, Method for producing a screen, characterized in that the impingement surfaces of the support (3) are inseparable from each other, for example by soldering, gluing or welding. The method according to any one of claims 14 to 16, Method of producing a screen, characterized in that the bending centerline lies on the side of the screen strip (2, 2 ') upon deformation of the support (3). The method according to any one of claims 1 to 13, The support 3 has its final end by elastic inverse deformation due to the combination of the support 3, the screen strips 2 and 2 'and the profile bars 1 and 1' before the profile bars are installed. A screen manufacturing method characterized by reaching a form. The method according to any one of claims 1 to 18, Method for producing a screen, characterized in that a clamping connection is also made between the forming surfaces of the screen strip (2, 2 ') and the profile bars (1, 1') by deformation of the support (3). The method according to any one of claims 1 to 19, At least part of the clamping connection is further reinforced by a connection that cannot be separated, such as for example by soldering. 21. A screen with a plurality of screen holes 7, made by the method according to any one of the preceding claims, comprising: The screen is At least two supports 3 provided with recesses 6 at defined intervals a, A joining contour, which is tightened parallel to each other in the recesses 6 of the support 3, the profile of one side (bottom surface) complementary to the recesses 6 in the support 3. Profile bars 1, 1 ′ with 10, wherein the profile comprises grooves 8 opposite to each other, and In addition to the screen holes 7 forming surfaces which at least partly correspond to the grooves of the profile bars 1, 1 ′ and are respectively fixed in parallel between each other between the profile bars 1, 1 ′. A screen strip (2, 2 ') with (5, 5') on its longitudinal sides as a part, Screen characterized in that the screen strips (2, 2 ') are not flat.

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