Cutting head of a pump
By setting different cutting edge lengths on the cutting head, the problem of easy clogging of the cutting device was solved, and more efficient pump operation and flow optimization were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WILO SE
- Filing Date
- 2022-06-23
- Publication Date
- 2026-05-29
Smart Images
Figure CN115523152B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a cutting head for a pump carrying a liquid containing solids, the cutting head being used in conjunction with a cutting ring and a cutting head base assigned to an impeller of the pump, wherein a plurality of cutting segments are provided on the outer peripheral surface of the cutting head base, each of the cutting segments having an axially extending cutting edge for crushing the solids, the cutting edges of the cutting head extending radially away from the cutting head base. Background Technology
[0002] Solid mixtures in liquids (such as sewage) can clog pumps or pipes. To prevent such clogging, a so-called cutting device is used. This device is located in front of the pump's suction area to break up the solids contained in the liquid.
[0003] Cutting devices known from the prior art typically have a stationary component (called the cutting face or cutting element) and a rotating component (called the cutting head). Depending on the application of the cutting device, circular, conical, or cylindrical cutting faces can be used. The cutting face (also called a cutting screen) has openings through which liquid flows to the impeller of the pump. A flat or conical configuration of the cutting face is called a cutting plate. A cylindrical configuration of the cutting face is called a cutting ring.
[0004] While such a cutting device may provide excellent cutting performance in its new condition, the device itself can become clogged, blocked by solids, or solids may become lodged in front of the pump's suction area, thus closing off the suction zone. Furthermore, cutting devices connected upstream of the pump typically negatively impact the pump's efficiency and characteristic curves due to their influence on the flow rate into the pump. Summary of the Invention
[0005] In light of this, the object of the present invention is to provide a cutting head for a pump carrying a liquid containing solids, which is safer to operate, reduces maintenance costs, and simultaneously enables the pump to achieve high hydraulic efficiency compared to solutions known from the prior art.
[0006] The object of the present invention is achieved by the features of a cutting head for a pump carrying a liquid containing solids. Advantageous configurations are given in specific embodiments.
[0007] Accordingly, this objective is achieved by a cutting head for a pump carrying a liquid containing solids, the cutting head working in conjunction with a cutting ring and a cutting head base assigned to an impeller of the pump. Multiple cutting segments are provided on the outer circumferential surface of the cutting head base, each having an axially extending cutting edge for crushing the solids. These cutting edges are radially away from the cutting head base and extend generally axially toward the impeller from the liquid inlet side of the cutting head opposite to the impeller. At least two of the cutting edges have two axially extending portions of different lengths.
[0008] The key to the proposed solution lies in achieving a higher and thus better pump characteristic curve through the use of cutting edges of varying cutter heads. Longer cutter heads interact with the impeller blades, while shorter cutter heads additionally affect the solids, resulting in better cutting results and reduced pump clogging. For example, even better cutting results can be achieved when one-third of the cutter head's cutting edge is made longer to interact with the impeller blades, and two-thirds is made shorter. Preferably, to achieve rotational symmetry, at least two cutter head cutting edges are made shorter, and multiples thereof are made longer.
[0009] A pump is generally a fluid machine that uses rotational motion and dynamic force to transport a medium that is primarily liquid. Preferably, the pump is designed as a rotary pump. In a rotary pump, in addition to the tangential acceleration of the medium / liquid, centrifugal force generated in the radial flow is used for transport; therefore, such a pump is also called a centrifugal pump. Preferably, the pump can be used in the hydraulic systems of buildings, for example, as a sewage pump.
[0010] During normal pump operation, the motor housing can be positioned above the pump housing, within which an impeller driven by the motor via a motor shaft is housed to transport fluid. The motor housing and pump housing are fixedly connected and / or can be designed as a single unit. Preferably, the motor shaft extends inward from the motor housing into the pump housing on the drive side, and / or the impeller on the drive side is fixedly connected to the motor shaft.
[0011] The liquid preferably includes water or other liquid media, such as sewage. The liquid may include solids, such as any kind of contaminant, particularly excrement, sediment, sludge, sand, or even smaller pieces of wood, shrubbery, textiles, rags, or the like. Preferably, the motor housing and / or pump housing are made of metal, especially cast iron or stainless steel, and / or of plastic.
[0012] The cutting ring is preferably designed with a disc-shaped cutting ring base with an opening through which the cutting head is guided. Preferably, the cutting head base is connected to the pump impeller, for example, screwed together. The cutting head can also be designed as a single piece with the impeller, for example, made of metal or plastic. The cutting segments preferably extend radially away from the cutting head base and / or are arranged at regular intervals and / or are designed as a single piece with the cutting head base. Preferably, axially extending cutting edges of the cutting head are provided on the radially outer side of the cutting segments, and these cutting edges preferably interact with the cutting teeth of the cutting ring to pulverize solids. Through the rotational movement of the motor shaft, for example, the textile obtained by the cutting edges of the cutting head can engage with the cutting teeth as a solid, thereby pulverizing the textile and thus preventing the pump from being blocked.
[0013] Preferably, at least two cutting edges of the cutting head extend from the liquid inlet side toward the impeller. Preferably, all cutting edges of the cutting head extend from the liquid inlet side toward the impeller. Particularly preferred is that at least one cutting edge of the cutting head extends over its entire extension between the liquid inlet side and the opposite, dispensed-to-the-impeller side. In contrast, cutting edges of the cutting head extending axially at different lengths preferably do not extend to the dispensed-to-the-impeller side and are correspondingly shortened. The cutting segment preferably extends from the outer circumferential surface, particularly the cylindrical one, toward the radial edge of the cutting head in a triangular manner in an axial plan view. The axial extensions of different lengths are preferably ≥30%, 40%, 50%, 60%, or 70%. Generally axial, in particular, means, for example, that may include a shaped bevel and / or that the cutting edge of the cutting head can be pivoted axially by 3%, 5%, or 10%. Furthermore, the cutting edges of the cutting head can be designed in a serrated form. Preferably, the shorter cutting edge of the cutting head is positioned between two longer cutting edges of the cutting head.
[0014] According to a preferred improvement, a first portion of the cutting edge of the cutting head extends substantially over the entire axial extension of the cutting head from the liquid inlet side, while a second portion of the cutting edge extends only over a portion of the entire axial extension of the cutting head from the liquid inlet side. The second portion may, for example, extend only half of the first portion. Preferably, the second portion extends over a portion such that the second portion of the cutting edge of the cutting head cannot interact with the blades of the impeller.
[0015] According to another preferred improvement, another portion of the second part of the axial extension is configured to have no cutting edge. In the region without a cutting edge, the cutting head preferably has a smaller radial outer diameter than in the region where a cutting edge is provided.
[0016] According to another preferred improvement, in another portion of the second part of the axial extension, the cutting segment gradually narrows in a teardrop shape, particularly on the side facing the cutting head and towards the impeller. The cutting segment gradually narrows, especially in its radial extension dimension, from the cutting edge of the cutting head towards the outer peripheral surface of the cutting head body. Preferably, the cutting segment transitions smoothly, particularly linearly, into the cutting head body, thereby achieving flow optimization.
[0017] According to another preferred improvement, the cutting head has a surrounding cylindrical joint on its axially facing side towards the impeller, which terminates flush with the cutting edge of the cutting head in terms of its radial outer diameter. In an axial cross-sectional view, the joint preferably slopes in an arc-shaped or exponential manner from the impeller-facing side toward the cutting head base. Particularly preferred is that the joint, especially in a rim-like design, gradually narrows in diameter away from its impeller-facing side and transitions particularly smoothly into the cutting head base. Preferably, the joint has the same radial diameter as the cutting edge or cutting segment of the cutting head and / or is implemented in one piece and / or smoothly transitions into it along the entire axial extension and / or along a longer cutting edge or cutting segment of the cutting head.
[0018] According to another preferred improvement, the cutting head base is designed to be cylindrical, with the cutting segment extending radially away from the outer circumferential surface of the cylinder, and the cutting edge of the cutting head extending to the outer diameter of the cutting head, particularly the joint. If the first portion of the cutting edge of the cutting head extends substantially over the entire axial extension of the cutting head from the liquid inlet side, then this means that preferably the cutting edge of the cutting head extends to the joint. Preferably, the cutting head is force-fitted and / or form-fittedly connected to the impeller.
[0019] According to another preferred improvement, particularly in the radial top view, the cutting segments extend radially away from the cutting head base to the corresponding cutting edge in a non-linear, particularly concave, and / or arc-shaped manner in the direction of rotation of the cutting head, and / or extend linearly radially away from the cutting head base to the cutting edge in the direction away from the rotation of the cutting head. This non-linear, particularly concave, and / or arc-shaped design allows for flow optimization along the direction of rotation of the cutting head, thereby improving pump efficiency.
[0020] According to another preferred improvement, the cutting segment and / or the cutting edge of the cutting head are inclined, particularly around the cutting head, on the liquid inlet side of the cutting head opposite the impeller. Further flow optimization can be achieved by tilting (e.g., at an angle of 15°).
[0021] This objective is also achieved by a pump having a cutting head as described above and a cutting ring fixedly mounted on the pump, the cutting ring having a plurality of cutting teeth that work together with the cutting edge of the cutting head to crush the obtained solids.
[0022] Such a pump achieves better flow at the impeller inlet, resulting in a higher pump characteristic curve because it reduces interference with the flow between the blades or the blade channels formed by them compared to designs known from the prior art. By using the cutting edges with the aforementioned cutting heads of varying lengths, larger diameter solids can be better retained until they are thoroughly pulverized by the outer cutting ring, resulting in better cutting results and a lower risk of clogging. Attached Figure Description
[0023] The invention will now be explained in detail with reference to the accompanying drawings and preferred embodiments.
[0024] In the attached diagram:
[0025] Figure 1 A pump according to a preferred embodiment of the present invention is shown in a partial cross-sectional view.
[0026] Figure 2 Two perspective views illustrate the cutting head of the pump according to a preferred embodiment of the present invention.
[0027] Figure 3 The cutting ring of the pump according to a preferred embodiment of the present invention is shown in two perspective views (top) and a partial cross-sectional view (bottom).
[0028] Figure 4 The impeller and cutting head of the pump according to a preferred embodiment of the present invention are shown in perspective view (left) and top view (right). Detailed Implementation
[0029] Figure 1 A pump according to a preferred embodiment of the present invention is shown in a partial cross-sectional view. The pump (implemented as a submersible sewage pump) has a cutting device connected upstream of the impeller 3, the cutting device including... Figures 2 to 4 The cutting head 1 and cutting ring 2 are shown in the diagram. The pump's cutting head 1, cutting ring 2, and impeller 3 do not necessarily have to be designed as described below. This means that the pump can, for example, have the cutting head 1 described below, but the cutting ring 2 and impeller 3 can be designed differently from those described below. In this regard, it is entirely feasible that, for example, the cutting ring 2 is designed as described below, the cutting head 1 need not be designed as described below. The same applies to the cutting ring 2 and impeller 3.
[0030] Figure 1A partial cross-sectional view shows a portion of the pump housing 4, above which is a housing (not shown) for the pump motor, which is located during normal operation of the pump. The motor drives an impeller 3 (not shown) via a motor shaft, which draws in liquid containing solids from the suction side 5 located below the pump housing 4. In this regard, the terms "axial" and "radial" as used below refer to the axial extension of the motor shaft, respectively.
[0031] The cutting head 1 is fixedly connected to the impeller 3, particularly by means of a cutting head bolt 6, and rotates accordingly with the impeller 3 during pump operation. A cylindrical cutting ring 2 surrounding the cutting head 1 is fixedly connected to the pump housing 4 relative to this by means of a plurality of cutting ring bolts 7. A radial seal is provided between the cutting ring 2 and the impeller 3. The cutting head 1 extends into the suction side 5, so that the pumped liquid first flows from the suction side 5 through the gap provided between the cutting head 1 and the cutting ring 2, so as to be subsequently conveyed through the impeller 3. Through the rotational movement of the cutting head 1 relative to the cutting ring 2, the solids contained in the liquid are pulverized before reaching the impeller 3.
[0032] Figure 2 Two perspective views illustrate the cutting head 1 of a pump according to a preferred embodiment of the invention. The left side shows a perspective top view of the cutting head 1 from the suction side 5, while the right side shows a perspective top view of the cutting head 1 from the side where it is assigned to the impeller 3. The cutting head 1 has a cylindrical, rotationally symmetrical, metal cutting head base 8 through which holes 9 for receiving cutting head bolts 6 for fastening at the impeller 3 extend axially.
[0033] Four cutting segments 11 arranged at regular intervals are provided on the outer peripheral surface 10 of the cutting head base 8. These cutting segments are designed as a single piece with the cutting head base 8. The cutting segments 11 extend radially away from the cutting head base 8. Furthermore, all cutting segments 11 extend axially toward the impeller 3 from the liquid inlet side 12 of the suction side 5 of the cutting head 1, which is opposite to the impeller 3, thereby forming an axially extending cutting edge 13 of the cutting head.
[0034] In the left figure, the cutting segments 11 or their cutting edges 13, arranged at approximately 180° opposite angles, extend axially to equal lengths, that is, they extend substantially from the liquid inlet side 12 of the cutting head 1 facing the suction side 5 to the opposite side 14 facing the impeller 3. However, the two cutting segments 11 or their cutting edges 13, arranged at 90° intervals between them, do not extend axially from the liquid inlet side 12 to the side 14. In other words, the two cutting edges 13 have axial extensions of different lengths relative to the other two cutting edges 13. The first portion of the cutting edge 13 extends substantially from the liquid inlet side 12 or over the entire axial extension of the cutting head 1, while the second portion extends only a portion of the entire axial extension of the cutting head 1 from the liquid inlet side 12.
[0035] In other words, the second portion of the cutting segment 11 is shortened by about half relative to the first portion, with the oppositely arranged cutting segments 11 being implemented accordingly. The shortened portion of the cutting segment 11 on the axial extension is implemented without the cutting edge 13 of the cutting head. The shortened cutting segment 11 has a constant radial diameter up to about half of the axial extension of the cutting head 1, and then gradually narrows in diameter in a teardrop shape toward the side 14 facing the impeller 3. The cutting head 1 has a surrounding cylindrical joint 15 on its axial side 14 facing the impeller 3, which is integrally implemented with the cutting head base 8 and terminates flush with the cutting edge 13 of the cutting head in terms of its radial outer diameter. The joint 15 gradually narrows in diameter from the side 14 toward the liquid inlet side 12 in a manner that transitions uniformly into the cutting head base 8.
[0036] In the direction of rotation toward the cutting head 1, the cutting segment 11 extends concavely radially away from the cutting head base 8 to the corresponding cutting edge 13 of the cutting head. Conversely, in the direction of rotation away from the cutting head 1, the extending cutting segment 11 extends linearly radially away from the cutting head base 8 to the cutting edge 13 of the cutting head. A similar description applies to the teardrop-shaped narrowing portion of the shortened cutting segment 11.
[0037] For further flow optimization, the cutting segment 11 and the cutting edge 13 of the cutting head are inclined at the liquid inlet side 12 of the cutting head 1 opposite to the impeller 3, such that... Figure 2 As can be seen from the above. In order to crush the obtained solids, the cutting head 1 can work together with the cutting edge 13 of its cutting head and the cutting ring 2 with multiple cutting teeth 16 fixedly set on the pump as described below.
[0038] Figure 3The cutting ring 2 of the pump according to a preferred embodiment of the present invention is shown in two perspective views (top) and a partial cross-sectional view (bottom). The cutting ring 2 has an annular cutting ring base 18 forming an opening 17. Figure 1 In the installed state shown, the cutting head 1 is guided through the opening 17. As previously described, the cutting ring 2 is fixed to the pump housing 4 of the pump in a positional manner by means of three cutting ring bolts 7 distributed around the opening 17 along the axial extension of the impeller 3.
[0039] A plurality of cutting teeth 16 are arranged at regular intervals around the opening 17 at the rotationally symmetrical cutting ring base 18. These cutting teeth have corresponding inner cutting edges 19 axially oriented in the direction toward the impeller 3 and outer cutting edges 19 axially oriented away from the impeller 3 in the direction toward the suction side 5 of the pump. The cutting edges 19 work together with the cutting edge 13 of the cutting head when the cutting head 1 rotates.
[0040] The corresponding three cutting teeth 16 extend axially inward into the pump housing 4 in the direction away from the cutting ring base 18 and towards the impeller 3, and the corresponding three cutting teeth 16 extend outward from the pump housing 4 in the direction towards the suction side 5, as shown in... Figure 1 As shown in the figure. Similarly, four, eight, twelve or more cutting teeth 16 can be provided, and the orientation of these cutting teeth is alternately outward and inward. In the axial extension direction, an inner cutting edge 19 and an outer cutting edge 19 are respectively designed around the opening 17 between the tip of the outer cutting tooth 16 and the tip of the inner cutting tooth 16.
[0041] The outward-extending cutting teeth 16 Figure 3 The cutting ring base 18 is shown below in the cross-sectional view below, while the inwardly extending cutting teeth 16 are shown above in the cross-sectional view above the cutting ring base 18. Figure 3 The perspective view at the upper right corresponds to this presentation and shows a view of the cutting ring 2 from the suction side 5, while the perspective view at the upper left shows a view of the cutting ring 2 from the pump housing 4.
[0042] At least in the outwardly extending cutting teeth 16, radially outwardly extending material recesses 20 are introduced accordingly after the cutting edge 19 along the rotation direction of the impeller 3. Such material recesses 20 are also introduced in the inwardly extending cutting teeth 16. This means that, in the top view, the outer diameters of the cutting teeth 16 extending wavyly or sinusoidally around the opening 17 are equal, while the inner diameters are larger in the regions of the material recesses 20 relative to the regions of the cutting teeth 16 without material recesses.
[0043] Alternatively or additionally, radially outwardly extending pouch-shaped axial recesses 22 are introduced into the cutting ring base 18 in the recesses 21 located between at least two outwardly extending cutting teeth 16. Here, pouch-shaped axial recesses 22 are introduced in both the recesses 21 located between the outwardly and inwardly extending cutting teeth 16. The recesses 22 extend radially outward from the bottom of the recess, thereby causing the cutting ring base 18 to flatten radially outward in the recesses 21. The material recesses 20 and recesses 21 are provided on all the cutting teeth 16 or between these cutting teeth, and can be manufactured by milling or by corresponding injection molding of the metal cutting ring 2.
[0044] For example, especially from Figure 3 As shown in the figure below, the outer cutting edge 19 of the recess 21 between the two outwardly extending cutting teeth 16 overlaps with the inner cutting edge 19 of the recess 21 between the two inwardly extending cutting teeth 16 in the axial direction. Thus, there is no radially surrounding, uninterrupted joint on the cutting surface of the cutting ring 2 formed by the cutting edges 19. Along the rotation direction of the impeller 3, the cutting angle of the cutting edge 19 gradually flattens outward from the cutting ring base 18 toward the tip of the cutting teeth 16.
[0045] The cutting angle (towards the cutting edge 13 of the cutting head) of the outer cutting tooth 16 or the outer cutting edge 19 is 55°, while the cutting angle of the inner cutting tooth 16 is 52.5°. Along the rotation direction of the impeller 3, the cutting angles are more gradual, at 20° externally and 10° internally. Each cutting tooth 16 extends outward from the cutting ring base 18 by at least 17 mm, with the inner cutting tooth 16 extending axially further away from the cutting ring base 18 than the outer cutting tooth 16. The cutting teeth 16 are also radially 'inclined', that is, gradually leveling off towards the opening 17 at 37° externally and 33° internally relative to the disc-shaped cutting ring base 18. Other cutting angles and dimensions are also conceivable.
[0046] Figure 4 The left-hand half-open perspective view and the right-hand half-open top view show the closed double-channel impeller 3 and the cutting head 1 of the pump according to a preferred embodiment of the present invention. Furthermore, the cutting head 1 is not in... Figure 4 The impeller 3 shown is fixedly connected along the axial extension of the impeller to a position that is not in the same location. Figure 4 The cutting rings 2 shown in the figure work together. The cutting head 1 is designed as previously described with a cutting head base 8 having a plurality of cutting segments 11, each of which has a cutting head cutting edge 13 extending particularly axially to crush solids, wherein the cutting head cutting edge 13 extends radially away from the cutting head base 8.
[0047] In a typical manner, the disc-shaped impeller 3 has two spirally extending blades 23, which extend from the central impeller opening 25 toward the inlet edge 24 of the cutting head 1 to the radial outer edge of the impeller. Figure 4 This is especially evident on the right side. The blade 23 is axially enclosed on one side by a radially extending support plate 26 on the motor side (which has a hub, not shown, for receiving the motor shaft of the pump), and on the other side by a radially extending cover plate 27 on the suction side, thus positioning the axially extending blade 23 between the support plate 26 and the cover plate 27, which are arranged parallel to each other. At the radially outer edge, the impeller 3 is radially open in a rectangular form in the side view between the support plate 26, the cover plate 27, and two adjacent blades 23.
[0048] For example, especially from Figure 4 As seen on the left, the cutting edge 13 of the cutting head is arranged spaced apart from the inlet edge 24. Furthermore, the inlet edge 24 is configured to be radially spaced outward from the inner edge of the impeller opening 25. Additionally, the cutting edge 13 of the cutting head is arranged radially ahead of and particularly radially overlaps with the inlet edge 24 along the rotation direction of the impeller 3, as shown in… Figure 4 The right side is shown by angle α. In other words, the inlet edge 24 of the impeller 3 and the cutting edge 13 of the cutting head are not on the same radial line. Angle α is, for example, ≤2.5°, 5°, or 10°, and especially α ≤2.5°, 5°, 10°, 15°, 20°, 30°, or 45°. The cutting edge 13 of the cutting head and the inlet edge 24 extend parallel to each other. "Radial overlap" specifically means that the inlet edge is arranged at at least partially at the same axial height as the cutting edge of the cutting head and / or at least partially in a common radial plane with the cutting edge of the cutting head. Preferably, the axial extension of the cutting edge of the cutting head is greater than the axial extension of the inlet edge.
[0049] Here, two blades 23 are provided as previously implemented, and the cutting head 1, guided through the impeller opening 25, has four cutting edges 13. However, only the cutting edge 13 of the four cutting edges 13 that is not shortened 11 interacts with the blades 23. In the axial direction, the shortened cutting segment 11 is positioned in front of the blades 23 on the suction side, so the cutting edge 13 of the shortened cutting segment 11 does not interact with the blades 23. In an alternative design, for example, with eight cutting segments 11, the impeller 3 conveniently has four blades 23. For radial sealing of the impeller 3, a cylindrical sealing gap (not shown) is provided between the suction side 5 of the impeller 3 and the pump housing 4. An additional seal is designed in which the cutting ring 2 at least partially surrounds the impeller 3 to form a conical sealing gap.
[0050] The described embodiments are merely examples, and these examples can be modified and / or supplemented in various ways within the scope of the claims. Each feature used to illustrate a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature used to illustrate an embodiment of a certain category can also be applied accordingly to embodiments of another category.
[0051] List of reference numerals
[0052] Cutting head 1
[0053] Cutting ring 2
[0054] Impeller 3
[0055] Pump housing 4
[0056] Inhalation side 5
[0057] Cutting head bolt 6
[0058] Cutting ring bolt 7
[0059] Cutting head base 8
[0060] Hole 9
[0061] outer periphery 10
[0062] Cutting segment 11
[0063] Liquid inlet side 12
[0064] Cutting head cuts edge 13
[0065] Side 14
[0066] Joint 15
[0067] Cutting teeth 16
[0068] Opening 17
[0069] Cutting ring matrix 18
[0070] Cut edge 19
[0071] Material recess 20
[0072] 21 Recesses
[0073] Depression 22
[0074] Leaf 23
[0075] Entrance edge 24
[0076] Impeller opening 25
[0077] 26 bearing plates
[0078] Cover plate 27
Claims
1. A cutting head (1) for a pump carrying a liquid containing a solid, the cutting head (1) being used in conjunction with a cutting ring (2) and having a cutting head base (8) assigned to an impeller (3) of the pump, wherein a plurality of cutting segments (11) are provided on the outer peripheral surface (10) of the cutting head base, each cutting segment having an axially extending cutting edge (13) for crushing the solid, the cutting edges being radially away from the cutting head base (8) and extending axially substantially toward the impeller (3) from the liquid inlet side (12) of the cutting head (1) opposite to the impeller (3), The first portion of the cutting edge (13) of the cutting head extends substantially over the entire axial extension of the cutting head (1) from the liquid inlet side (12), while the second portion of the cutting edge (13) extends only over a portion of the entire axial extension of the cutting head (1) from the liquid inlet side (12), and In another part of the second portion of the axial extension, the cutting segment gradually narrows toward the side (14) facing the impeller (3) of the cutting head (1).
2. The cutting head (1) according to claim 1, wherein in the other part of the second part of the axial extension, the cutting segment gradually narrows in a teardrop shape toward the side (14) of the cutting head (1) facing the impeller (3).
3. The cutting head (1) according to claim 1, wherein the cutting head (1) has a surrounding cylindrical joint (15) on its axially facing side of the impeller (3), the joint terminating flush with the cutting edge (13) of the cutting head in terms of its radial outer diameter.
4. The cutting head (1) according to claim 3, wherein the joint (15) gradually narrows in diameter on the side away from its facing impeller (3) and transitions into the cutting head body (8).
5. The cutting head (1) according to claim 1, wherein the cutting head base (8) is designed to be cylindrical, the cutting segment (11) extends radially away from the cylindrical outer peripheral surface (10) and the cutting edge (13) of the cutting head extends to the outer diameter of the cutting head (1).
6. The cutting head (1) according to claim 1, wherein the cutting segment (11) extends radially away from the cutting head base (8) in a nonlinear manner in the rotation direction of the cutting head (1) to the corresponding cutting head cutting edge (13), and / or the cutting segment extends radially away from the cutting head base (8) in a linear manner in the rotation direction away from the cutting head (1) to the cutting head cutting edge (13).
7. The cutting head (1) according to claim 6, wherein the cutting segment (11) extends concavely radially away from the cutting head base (8) in the rotation direction of the cutting head (1) to the corresponding cutting head cutting edge (13).
8. The cutting head (1) according to claim 1, wherein the cutting segment (11) and / or the cutting edge (13) of the cutting head is inclined at the liquid inlet side (12) of the cutting head (1) opposite to the impeller (3).
9. A pump having a cutting head (1) according to any one of claims 1 to 8 and a cutting ring (2) fixedly disposed on a pump housing, the cutting ring having a plurality of cutting teeth (16) that work together with the cutting edge (13) of the cutting head to crush the obtained solids.