DD299949A5 - FINE-SCREEN AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The invention relates to a Feinstsichter and the method for its preparation. The fine grader serves for fine classification of disperse solids in the finest grain range d972 to 50 m. According to the invention, the technical object is achieved in that the slits distributed rotationally symmetrically over the circumference of the ultrafine have a slot width of less than or equal to 3 mm. The slots should have a larger width on the outer periphery of the Feinstkorb sifter than on the inner circumference. Particularly favorable here has a ratio of aeuszerer to inner slot width of 3: 2 to 2: 1 proved. The slots have a larger length on the outer periphery of the main body than on the inner circumference. They have either the shape of a trapezoid or a limited by two parallel secants circular section. The method for producing such classifiers is characterized according to the invention by the fact that the slots in one or more operations by cutting shaping, such as. B. milling, or by electrothermal ablation, such. B. by electroerosive ablation or by electron beam, rotationally symmetric of auszen inwardly into the body are incorporated and then carried out a balancing of the classifier. Slot width; Slot shape; Schlitzflaeche; cutting shaping; electrothermal removal; narrower grain band; lower classifier speed; lower sifter diameter; Fine classification}

Description

For this 1 page drawings

Field of application of the invention

The invention relates to a fine-grader and the method for its production. The finesseer is used for fine classification of disperse solids in the finest grain range d ₈ ; = 2 to 50 pm.

Characteristic of the known state of the art

The well-known fine classifiers for fine classification in the finest grain range d ₈₇ = 2 to 50 μm can be subdivided into two different structural designs: '

- Feinstkorbsichter with a small diameter, which is operated at high speeds,

- Feinstkorbsichter with a large diameter, which is operated with a low threat number.

The known finetuniversers generally have either straight or zigzag-shaped slots whose end faces extend parallel to the end faces of the classifier base body.

The theoretical basis of the two structural designs is based on the fact that the separation grain size of the Feinstkorbsichters d _T can be calculated according to the following equation:

d _T = K-1 / (Ds-ns ² ),

where K-constant

Ds - sifter diameter

ns - Sichtersrehzar · I mean.

It can be seen from the equation that the separation grain diameter in the classifier can be reduced by increasing the classifier speed ns.

The disadvantage, however, is that at higher Sichtersdrehzahl or higher peripheral speed increased wear of the classifier and thus a shortening of the life, especially the camp occurs. It can also be seen from the equation that the grain diameter of the fine grain sifter is inversely proportional to the sifter diameter. The increase of the sifter by means of the sessor causes an increase of the peripheral speed of the sifter wheel and thus a centrifugal force increase. Since these centrifugal forces must be absorbed by the bearing, bearings with high load ratings and large bearing diameter are required. Therefore, a fineness improvement by increasing the Sichterdurchmessers is technically difficult to achieve.

The known Feinstkorbsichter be prepared either by casting or by welding, so that due to the manufacturing technology only relatively large slot widths are feasible, make the large Sichterdurchmesser or -drehzahlr required to ensure sufficient fineness of the disperse solids in the classification. The known FeinstkorbsicNer have an outer slot width of> 5mm and an inner slot width of> 2.4 mm. From "TURBOPLEX-FeinstsichterType 100 ... 1000 ATP", Alpine AG / FRG, brochure 37/1 d classifiers are known that work for the reasons mentioned with sizer diameters of 100 mm with speeds up to 11500 min '' (type 100 ATP ). With this design finenesses d ₈ 7 = 4 pm are achievable. The TURBOPLEX fine classifier type 50 ATP can be used at speeds of 22 000 min " ¹ for particle sizes up to 2.5 ppm (" Mechanical Process Engineering ", Alpine AG, Prosp; <t0i7 / Öd)

SCHUBERT, H .: "Preparation of solid mineral raw materials", Bond I, VEB German publishing house for basic industry Leipzig, 4th edition, 1989, it is apparent that the separation range such Sichtor between 2 and 80μπι and for the separation grain size primarily the speed A separation grain size of 4 pm and smaller thus leads to the fact that it is necessary to drive at very high classifier speeds, which result in a high mechanical load on the mechanical wear elements the deneitigon state of the art will be received.

Object of the invention The aim of the invention is to make the finest classification with Feinstkorbsichtern with simple means. Explanation of the essence of the invention The technical object of the invention is to develop a fine-vision observer and a method for its partial separation,

the guaranteed compared to known Feinstkorhsichtern with the same diameter even at low Sichtersrehzahlen a high fineness of the classified solids and the process ensures easy production.

According to the invention, the technical problem is solved in that the rotationally symmetrical over the circumference of Fine sliver distributed -> π ^ '., Slots have a slot width of less than or equal to 3mm. The slots should be on the

outer Umfcng the i οι istkorbsichter have a greater width than the inner circumference. A ratio of outer to inner slot width of 3: 2 to 2: 1 has proven particularly favorable. The slots have on the outer circumference dt s

Body on a greater length than on the inner circumference. You have in longitudinal section either the shape of a trapezoid

or the one or two parallel secants bounded circular section.

Due to the small slot width and the surface shape of the slot, it is caused by the from outside to inside

decreasing cross-section of the slot increases the flow resistance in the slots and the sucked

Air volume flow affects, resulting in that the Tronnkorngrößenendurchmesser is reduced. Thus, the possibility has been created, with the same Sichterdurchmesser and the same Sichtergeschwindigkeit one

To obtain much finer end product or to obtain an end product with a required fineness compared to known Feinstsichtern at the same Sichterdurchmesser to work with a significantly reduced Sichterdrehzahl so that the peripheral speeds and thus the centrifugal forces are reduced. As a result, a wear-poorer operation of this Feinstsichters guaranteed and increases the life of the entire edition.

The method for producing such classifier is inventively characterized in that the slots in or

several operations by cutting shaping, such. B. milling, or by electrothermal ablation, such. B.

be machined by electron-free erosion or electron beam, rotationally symmetric from outside to inside in the body and then balancing the classifier takes place. In the first step, the incorporation of the larger slit width and in the second operation, the incorporation of the smaller slit width. The cutting shaping can be advantageously carried out with a rotating circular cutter. Due to the circular shape of this

Milling cutter at the same time the surface of the slot according to the invention is realized. The electrothermal ablation is carried out so that the

Slot surface according to the invention, in particular the trapezoidal shape arises.

The inventive method for producing the Feinstsichters allows the creation of the slot shape in a simple manner

dos Feinstsichters invention.

embodiment

The invention will be explained in more detail with reference to an embodiment. The solution according to the invention is compared with a known Feinstkorbsichter.

In order to illustrate the fine-grained separator according to the invention, such is shown in cross-section in FIG. 1 and in longitudinal section in FIG. From Fiour 1 it is clear at the same time that the fine-graining machine was produced in two work steps. For this purpose, a milling with a width of 3 mm and then a milling with a width of 1.8 mm was carried out concentrically with a circular cutter first. Due to the manufacturing process, the fine-graining machine has the area of a circular cut-out bounded by two parallel secants. This form has the advantage that from the outside to the inside * ne cross-sectional movement results, which causes the flow resistance increases and contributes to the separation grain size is further reduced at the same Sichterdurchmesser and same Sichtersrehzahlen. The known Feinstkorbsichter has an outer slot width of 5.04 mm and an inner slot width of 2.43 mm in a rechteckförrr.igen surface. By the manufacturing method according to the invention, it is possible to reduce the outer slot width to 3mm and the inner slot width to 1.8mm and so to arrange more slots over the circumference of the Feinstkorbsichters and on the other to realize the necessary cross-sectional constriction. Accordingly, the ratio of the outer slot widths is K = 3 / 5.04 = 0.595 and that of the inner slot widths K = 1.8 / 2.43 = 0.797. The Feinstsichter produced according to the invention allows, with a sifter diameter of 100 mm and a required fineness of d ₈₇ = 4μσ), the classifier speed of 11500min "'in a fine classifier of the type 100 ATP Alpine / Germany or of 8500min" ¹ with a classifier from the ZAB Dessau on 5000min " ¹ to reduce.

Claims (6)

1. Feinstsichter consisting of a Grundkörpei, id ι rotationally symmetric distributed over the circumference slots are arranged, chi 'urch characterized in that the slots have a slot width v? "Smaller than 3 mm and the outer circumference of the body has a greater width and length than on the inner circumference. 2. fine-gauge according to claim 1, characterized in that the slots have a ratio of outer to inner slot width of 3: 2 to 2: 1. 3. Feinstsichter according to claim!, Characterized in that the slots in longitudinal section have the shape of a trapezoid or the one or by two parallel secants limited circular cutout. 4. A method for producing the Feinstsichters, characterized in that the slots are rotationally symmetrical over the circumference of the body distributed by machining shaping or electrothermal ablation from the outside to the inside are incorporated. 5. The method according to claim 4, characterized in that the cutting shaping takes place with a circular cutter, wherein in a first operation, the larger slot width and in a second operation, the small slot width is milled. 6. The method according to claim 4, characterized in that the electrothermal ablation is carried out by electroerosive ablation or by electron beam.