Separating wheel with hybrid separating wheel blades for wear protection

Abstract

The invention relates to a separation wheel having mixing separation wheel blades, each of which consists of at least one blade base body, the radially outer region of which is provided with at least one protective strip made of an anti-wear material at least on the front side during normal operation, the invention relates to a blade comprising at least one shroud strip having a wear resistant material, which differs from the material of the blade carrier, preferably a carbide or ceramic material, characterized in that the at least one shroud strip has at least one, preferably a plurality of, form-fitting elements, each form-fitting element engaging with a respective form-fitting element of the blade base body.

Description

Technical Field

[0001] The invention relates to a centrifugal separator or a separating mill having an improved separating wheel, and a separating wheel for such a separator. Background Art

[0002] Separator mills operate with high-speed rotating wheels, one of which is a separator wheel and the other is for grinding. The two wheels are arranged in the same chamber to achieve crushing and classification of the feed. The separator wheel is usually drum-shaped. Its outer cover surface is formed by a plurality of closely adjacent separation wheel blades, and the separation wheel blades are held between two separation wheel discs. Corresponding channel gaps are respectively left between adjacent separation wheel blades, which are called "separation gaps".

[0003] The sorting is usually carried out as follows: smaller particles, which only generate a small centrifugal force during the circular motion, are introduced into the interior of the separation wheel by the carrier gas. These smaller particles then form the fine material fraction, which is discharged through the end face of the separation wheel with the carrier gas.

[0004] This does not work for larger particles. For a pure separator, the coarse particles are discharged via the coarse material outlet as a usable portion or for regrinding. For a separation mill, the coarse particles will hit the operating area of ​​the grinding wheel (Sichterrad) (usually even repeatedly), and thus be crushed. In this way, the newly generated smaller particles are introduced into the inside of the separation wheel by the carrier gas flow. After the collision, the remaining larger particles will also experience further collisions quickly and continuously. Thus, the remaining larger particles are further crushed and separated. However, they are also therefore further accelerated in the circumferential direction.

[0005] This also causes the particles that are still being ground to hit the separator wheel blades.

[0006] It can be easily seen that the separating wheel blades, which have a breaking effect here, are subjected to strong impact wear, in particular in their radially outward regions, which are located upstream in the direction of rotation.

[0007] In order to control wear, it is known to manufacture the separator wheel blades from particularly wear-resistant materials, for example ceramic or carbide materials. However, these materials are more sensitive to notch impacts. When solid separator wheel blades are made of hard materials, such separator wheel blades occasionally break. This occurs in particular when particularly large particles strike the separator wheel blades without them being immediately damaged. Due to the high operating speeds, blade breakage often leads to severe subsequent damage.

[0008] In view of this, people have also considered using mixing and separating wheel blades.

[0009] For these separator blades, the separator blade base is still made of steel. To prevent wear, a shroud strip made of ceramic or carbide material is bonded to the most stressed areas of the separator blade. This has the advantage that even if the shroud strip breaks, no fragments of the shroud strip or only minimal fragments are released in the separator, thus largely preventing subsequent damage.

[0010] However, problems arise again and again. If particularly high-strength adhesives are used to bond the strips, regular replacement of the strips becomes very time-consuming. If adhesives are used that produce an insufficiently strong connection, the risk of the strips accidentally falling off increases. This is associated with damage caused by the breaking of solid blades. Summary of the invention

[0011] Purpose of the invention

[0012] In view of this, the object of the present invention is to provide a separating wheel with a guard plate which can be replaced more easily but is still as reliable as possible for separating mills or separators which primarily only perform separation but are nevertheless subject to wear.

[0013] Solution according to the invention

[0014] According to the invention, a separator wheel with hybrid separator wheel blades is proposed. Each separator wheel blade comprises a blade base. The blade base can be made in one piece or in multiple pieces. The blade base is preferably made of wear-resistant steel, the wear resistance of which is improved compared to construction steel. The radially outward region of each blade base, at least on its front side during the expected operation, carries at least one guard plate strip made of wear protection material, the material of which is different from the material of the blade carrier. Ideally, a carbide material or a ceramic material is used to manufacture the guard plate. According to the separator wheel blade of the invention, it is characterized in that at least one guard plate strip has at least one (preferably multiple) form-fitting element formed with it (preferably integrally formed). One or more form-fitting elements are respectively engaged with corresponding form-fitting elements of the blade base. In other words, the form-fitting elements on the side of the guard plate strip are made of the same, particularly wear-resistant material as the one or more guard plate strips. As a result, the form-fitting elements themselves become more wear-resistant, because the complementary form-fitting elements in the blade base also benefit indirectly.

[0015] In this way, bonding can only be omitted in exceptional cases, but the bonding effect is significantly enhanced.

[0016] The one or more form-fitting elements are preferably selected such that they are able to hold the shroud strip on the blade carrier during ongoing operation even in the event of a failure of the adhesive bond. They are preferably designed such that a portion of the stresses in the radially outward direction are kept away from the adhesive bond site even during normal operation. In this way, a less robust adhesive can be used, so that the corresponding shroud strip can be separated from the blade base body more quickly or more easily, respectively, in order to replace it. Nevertheless, the reliability of the adhesive bond is still increased and the possibility of its failure is no longer present.

[0017] Preferred design options

[0018] Ideally, the bonding is not purely optional, so that the shroud strip is also additionally bonded to the blade base body. This creates an effect that can be described with the keyword "laminated glass effect": If the shroud strip is strongly impacted by larger particles, it may break into pieces. But all larger fragments remain in place instead of being thrown back and forth in the separator and causing subsequent damage.

[0019] Ideally, the adhesive connecting the shroud strip and the blade base has such heat resistance that the connection between the blade base and the shroud strip can be severed by heating the mixing and separating wheel blade to a certain temperature, but this temperature does not significantly affect the microstructure of the blade base.

[0020] Preferably, the heating temperature ranges from at least 220°C to less than 280°C.

[0021] In this way, the adhesive can be released very efficiently during the replacement of the cover strip.

[0022] The form-fitting elements preferably interact in such a way that centrifugal forces acting on the cover strip during operation are absorbed to a large extent, preferably substantially and ideally completely by the form-fitting elements.

[0023] This significantly reduces the bonding burden and low-quality adhesives are sufficient.

[0024] Ideally, the blade base body has a groove into which the guard strip can be inserted flush, i.e. preferably the guard strip forms together with the blade base body an all-round, at least substantially smooth-surfaced separator wheel blade. Thus, there is no specific occurrence point where powder can accumulate, which could result in an imbalance if powder accumulates in large quantities.

[0025] Preferably, the groove is formed substantially on the large surface of the blade base body that is located in front during operation, and the guard strip is placed in a flush manner in this groove. The groove preferably extends over at least the radially outermost 25% of the large surface of the blade base body. In this way, the radially front part of the two large surfaces (which are subjected to most particle impacts) is well protected.

[0026] It is particularly advantageous if at least one form-fitting element of the cover strip is formed in the region of its end closest to the rotational actuation axis. The form-fitting element can be formed relatively large and insensitive in this region, and any resulting notch effects do not radiate or radiate significantly into high-stress regions, where fractures can even occur due to the impact of oversized particles. In addition, the form-fitting element is located outside the regions most affected by wear.

[0027] For the same reason, it is also advantageous when the form-fitting element is a projection which projects (preferably in radial direction) from the narrow surface of the cover strip which is closest to the rotational operating axis.

[0028] It is advantageous if the thickness of the shroud strip in the circumferential direction is smaller than the cross section of the blade basic body to which it is adhered.

[0029] Independently of the above, the use of a shroud strip having at least one form-fitting element for shrouding (ideally with a smooth surface) a separating blade of a separating wheel according to one of the preceding claims is also claimed by hanging the shroud strip in the blade base body.

[0030] A separating mill is also claimed for impact grinding and sorting of preferably soft to medium hard materials (ideally up to 3.5 Mohs hardness), the separating mill being ideally located in a housing in which the mill and the separator are integrated and having at least one separating wheel according to one of the established claims.

[0031] Further modes of action, advantages and design options of the invention emerge from the following exemplary embodiments, which illustrate the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The sectional view of a turbine separator is shown, in which the separating wheel according to the invention can also be used, for example for separating particularly abrasive materials.

[0033] Figure 2 The notches of a separating wheel according to the invention are shown.

[0034] Figure 3 A detailed view of a separating wheel according to the invention is shown.

[0035] Figure 4 A separator wheel blade is shown with a blade base body on which a shroud strip is carried. DETAILED DESCRIPTION

[0036] For a turbine separator, which is used primarily for separation purposes (hereinafter as an exemplary embodiment), the situation is similar to that of the above-mentioned separation mill. This is because these devices are comparable in their general operating principles. Unless otherwise stated, the content described below also applies to the grinding separator, which is also protected by the claims.

[0037] Figure 1 A vertical separator with a separating wheel according to the invention is shown.

[0038] The mixture of coarse and fine material is brought in from the bottom with the aid of a carrier gas flow via the feed pipe 3. The feed pipe 3 ends in the center of the separator drum 6. The feed pipe 3 is at a distance from the inner circumferential mantle surface of the separator drum 6, along which the coarse material fraction is discharged.

[0039] From there, the coarse material portion reaches a separation chamber 4 which is formed between the outer circumference of a separation wheel 5 and a separation drum 6 which surrounds the separation wheel 5 .

[0040] exist Figure 1 The separating wheel 5 can already be clearly seen in FIG. 5 , whose separating wheel blades 9 are spaced apart from one another.

[0041] The fine material entrained by the carrier gas flow can pass through the separator gap between adjacent separator wheel blades 9. The fine material enters the interior of the separator wheel 5 in this way and is then discharged by the carrier flow via the perforated end face of the separator wheel 5 into the duct 7 forming the outlet for the fine material portion. The coarse material cannot pass over the separator wheel blades 9 into the interior of the separator wheel 5. Instead, the coarse material is accelerated in the circumferential direction by the separator wheel 5. The coarse material then falls out along the inner circumferential outer cover surface of the separator drum (mostly in a downwardly inclined spiral line) into the duct 8 forming the outlet for the coarse material portion.

[0042] Particularly when separating harder or abrasive materials, the separating wheel blades are also at risk of wearing in their radially outward leading edge region (in the direction of movement), although the intensity of the wear may be significantly lower than in the case of a separating mill.

[0043] Figure 2 The notch of the separating wheel 5 is shown, which is actually Figure 1 It can be clearly seen in FIG. 5 that the separation wheel 5 is drum-shaped. Its outer cover surface is composed of a plurality of separation wheel blades 9 that are closely adjacent to each other. Figure 2It can be seen more clearly that adjacent separation wheel blades 9 leave respective channel gaps 10 between each other. The separation wheel blades 9 closely adjacent to each other are held between two separation wheel discs 11, each of which is usually arranged on the end face of the separation wheel in a form-fitting manner.

[0044] It can be seen that the separating wheel blades 9 have large surfaces 12. The large surfaces 12 each define a separator gap through which the carrier gas flow can flow into the separating wheel together with the fine material fraction. The separating wheel blades have a radially outwardly directed narrow surface 13 over the entire outer casing.

[0045] from Figure 3 It can be clearly seen that the separating disc 11 is in many cases also provided with a shielding, usually with a carbide coating or a ceramic covering.

[0046] Figure 4 An exemplary embodiment of one of the separating wheel blades 9 according to the invention is shown.

[0047] It can be clearly seen that the separating wheel blade 9 comprises a blade base body 14. This blade base body 14 is usually made of steel. It has proven to be ideal if this steel is already hardened steel or a steel that provides increased wear resistance in any other way.

[0048] It can be clearly seen that the blade base body 14 - essentially on its large surface that is placed forward during operation - has a recess 15 formed in a stepped manner. This provides free space for the insertion of a preferably smooth-surfaced cover strip 16. The cover strip is preferably designed as a single piece. The blade base body usually completely supports the cover strip on the rear side opposite its large free surface. Preferably, the blade base body also additionally supports the cover strip on one (or preferably even three) of its narrow end faces and side faces.

[0049] Optionally, the insertion of the smooth surface means that the shroud strip is inserted such that it does not form edges or protrusions anywhere, which could protrude beyond the blade base body and on which material to be separated could accumulate.

[0050] Here the radially outward end faces of the separator wheel blades can also be clearly seen.

[0051] It can be seen that according to the invention, the guard plate strip has at least one (preferably a plurality of) form-fitting elements 17. The form-fitting element 17 protrudes in the area of ​​the end of the guard plate strip that is closest to the rotational operating axis. The form-fitting element 17 has a shape similar to the form-fitting element of a puzzle piece. This means that the corresponding form-fitting element is a flat structure. The flat structure is connected to the actual guard plate strip via a "neck" that is narrower than the remaining flat structures. The narrow edge surface of the flat structure establishes a form-fitting connection with the blade base, which is of great significance for the present invention.

[0052] It can be seen here that the corresponding form-fitting element 17 is continuously rounded and therefore has no substantially angular edges. In this way, the notch effect, which would weaken the form-fitting element, can be kept low, which is particularly important for the cover strip made of ceramic material. The form-fitting element used here is therefore superior to other form-fitting elements, such as pins, each of which is inserted into the blade base body through a hole in the cover strip, thereby ensuring a form-fitting anchoring.

[0053] As already mentioned above, the complementary recess 18 on the blade basic body 14 is assigned to the form-fit element 17 .

[0054] The positive-fit element 17 and the groove 18 interact in such a way that the cover strip cannot be thrown radially outwards even if the adhesive bonding for additionally holding the cover strip fails.

[0055] Ideally, the work distribution in terms of increasing the required holding force of the cover strip is such that not only a small part, but a large part, or even a major part, of the centrifugal forces acting in the radially outward direction is absorbed by the form-fitting element. Adhesion is at least the main reason, and in most cases even almost the only reason, that the cover strip cannot be released from its form-fitting radial anchoring.

[0056] It is also worth noting that it is particularly advantageous when the groove 15 does not completely reach the short end face of the blade base body 14, such as Figure 4 This is because the guard strip can be replaced even if the blade base body 14 is still held by the separation wheel disc at its short end edge.

[0057] Reference numerals list

[0058] 1 Vertical separator

[0059] 2 Not used

[0060] 3 Feed pipe

[0061] 4 Separation chamber

[0062] 5 Separation wheel

[0063] 6 Separation drum

[0064] 7 Pipe for discharge of the fine material fraction

[0065] 8 Pipe, forming the outlet for the coarse material portion

[0066] 9 Separator wheel blades

[0067] 10 Separation gap

[0068] 11 Split Roulette

[0069] 12 Large surface of the separator blades

[0070] 13 The radially outward narrow surface of the separator blade

[0071] 14 Blade base

[0072] 15 Grooves

[0073] 16 Guard strip

[0074] 17 Form-fitting components

[0075] 18 Supplementary grooves

Claims

1. A separation wheel (5) with mixing separation wheel blades (9), each mixing separation wheel blade (9) consisting of at least one blade base body (14), wherein the radially outward region of the blade base body (14) is provided with at least one guard strip (16) on at least one side which is located in front during normal operation, wherein the guard strip (16) is made of a wear-resistant material which is different from the material of the blade carrier, the wear-resistant material being ideally a carbide material or a ceramic material, characterized in that At least one cover strip (16) has at least one, preferably a plurality of, positive-fit elements (17), each of which engages with a corresponding positive-fit element (17) of the blade basic body (14).

2. The separation wheel (5) according to claim 1, characterized in that: The shroud strip (16) is additionally glued to the blade base body (14).

3. The separation wheel (5) according to claim 2, characterized in that: The adhesive connecting the guard plate strip (16) and the blade base (14) has heat resistance and is configured so that the connection between the blade base (14) and the guard plate strip (16) can be released by heating the mixing and separation wheel blade (9) to a temperature that does not significantly affect the microstructure of the blade base (14).

4. A separating wheel (5) according to any one of the preceding claims, characterized in that The form-fitting elements (17) interact in such a way that centrifugal forces acting on the cover strip (16) during operation are absorbed by the form-fitting elements (17).

5. A separating wheel (5) according to any one of the preceding claims, characterised in that The blade base body (14) has a groove, into which the shroud strip (16) can be inserted in a flush manner.

6. The separation wheel (5) according to claim 5, characterized in that: The groove (15) is formed substantially on the large surface of the blade basic body (14) which is located forward during operation, and the groove (15) preferably extends at least over the radially outermost 25% of the large surface of the blade basic body (14).

7. The separation wheel (5) according to claim 5 or 6, characterized in that: At least one form-fitting element (17) of the cover strip (16) is formed in the region of its end closest to the rotary actuation axis.

8. The separation wheel (5) according to claim 7, characterized in that: The form-fitting element (17) is a projection which projects, preferably in the radial direction, from the narrow surface of the cover strip (16) which is closest to the rotary operating axis.

9. A separating wheel (5) according to any one of the preceding claims, characterized in that The thickness of the guard plate strip (16) in the circumferential direction is smaller than the cross section of the blade base (14) to which it is bonded.

10. Use of a guard strip (16) having at least one form-fitting element (17) for providing a guard, ideally with a smooth surface, to a separator wheel blade (9) of a separator wheel (5) according to any of the preceding claims by hanging the guard strip (16) in a blade base (14).

11. A separating mill for impact grinding and classifying preferably soft to medium-hard materials, ideally up to 3.5 Mohs hardness, comprising at least one separating wheel (5) according to any one of claims 1 to 9.

Images