Treatment element for a treatment element shaft of a screw machine, and method for producing a treatment element

Abstract

A treatment element for a treatment element shaft of a screw machine comprises a main body with an outer wall, wherein the outer wall has a first wall section and a second wall section and wherein the first wall section is harder than the second wall section.

Claims

1. A treatment element for a treatment element shaft of a screw machine, comprising: a main body with an outer wall, wherein: the outer wall has several first wall sections and several second wall sections, wherein the first wall sections are harder than the second wall sections, the first wall sections are of strip-like form such that an aspect ratio of each of the first wall sections is at least 5, wherein the first wall sections and the second wall sections are oriented parallel to one another and are arranged alternately with respect to one another, and the treatment element is one of the following: a screw element, wherein a main extent direction of the first wall sections is oriented obliquely with respect to a helical line of the screw element, or a kneading element, wherein a main extent direction of the first wall sections is oriented obliquely with respect to an axis of rotation of the treatment element and obliquely with respect to a cross-sectional area of the kneading element.

2. The treatment element according to claim 1, wherein the first wall sections are harder by at least 50 HV 10 than the second wall sections.

3. The treatment element according to claim 1, wherein only the first wall sections lie on a lateral surface of revolution of the main body.

4. The treatment element according to claim 1, wherein the outer wall has a ridge section and a base section, wherein at least one of the first wall sections and the second wall sections are arranged on at least one of the ridge section and on the base section.

5. The treatment element according to claim 1, wherein the second wall sections are oriented at least one of parallel and perpendicular to the axis of rotation of the treatment element.

6. The treatment element according to claim 1, wherein at least one of the first wall sections and the second wall sections surrounds the axis of rotation of the treatment element over at least 180?.

7. The treatment element according to claim 1, wherein at least one of the first wall sections and the second wall sections are produced by material deposition.

8. The treatment element according to claim 1, wherein at least one of the first wall sections and the second wall sections form a profiling of the outer wall.

9. A treatment element shaft, having: at least one treatment element according to claim 1, and a support shaft to which the at least one treatment element is rotationally conjointly attached.

10. A screw machine, comprising: at least one treatment element shaft according to claim 9, and a housing, having a housing main body, and at least one housing bore which is formed in the housing main body and in which the at least one treatment element shaft is arranged at least in certain sections.

11. A method for producing the treatment element according to claim 1, comprising the steps: providing the main body with the outer wall, and forming the first wall sections and the second wall sections of the outer wall such that the first wall sections are harder than the second wall sections.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a partially sectional side view of a multi-shaft screw machine having a housing and having two treatment element shafts, which each comprise multiple treatment elements,

(2) FIG. 2 shows a partially sectional plan view of the multi-shaft screw machine in FIG. 1,

(3) FIG. 3 shows a cross section through the multi-shaft screw machine along the section line III-III in FIG. 2,

(4) FIG. 4 shows a side view of a treatment element in the form of a screw element according to a first exemplary embodiment,

(5) FIG. 5 shows a cross section of the screw element along the section line V-V in FIG. 4,

(6) FIG. 6 shows a side view of a treatment element in the form of a screw element according to a further exemplary embodiment,

(7) FIG. 7 shows a cross section of the screw element along the section line VII-VII in FIG. 6,

(8) FIG. 8 shows a side view of a treatment element in the form of a kneading element according to a further exemplary embodiment,

(9) FIG. 9 shows a cross section of the kneading element along the section line IX-IX in FIG. 8,

(10) FIG. 10 shows a side view of a treatment element in the form of a kneading element according to a further exemplary embodiment, and

(11) FIG. 11 shows a cross section of the kneading element along the section line XI-XI in FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(12) A screw machine 1 for the preparation of a substance or plastics material 2 will be described on the basis of FIG. 1 to FIG. 3. The plastics material may comprise additives 3. The screw machine 1 is in the form of a multi-shaft screw machine, in particular in the form of a two-shaft screw machine.

(13) The screw machine 1 has a first treatment element shaft 4 and a second treatment element shaft 4. To distinguish between the components of the first treatment element shaft 4 and of the second treatment element shaft 4, the reference designations relating to the second treatment element shaft 4 have the suffix . Along a conveying direction 5, the treatment element shafts 4, 4 each comprise multiple treatment elements 6 to 15 or 6 to 15 respectively, which are arranged in series. The treatment element shafts 4, 4 are arranged rotatably in a housing 16 of the screw machine 1. The housing 16 comprises a housing main body 16a. In the housing main body 16a, there are arranged two mutually parallel housing bores 17, 17. The first treatment element shaft 4 is arranged in a first housing bore 17, and the second treatment element shaft 4 is arranged in a second housing bore 17. The first housing bore 17 and the second housing bore 17 are oriented parallel to one another and overlap one another such that, in cross section, they have the shape of a figure of eight lying on its side. The treatment element shafts 4, 4 are arranged concentrically with respect to the housing bores 17, 17.

(14) The first treatment element shaft 4 has a first support shaft 18 to which the treatment elements 6 to 15 are rotationally conjointly attached. The second treatment element shaft 4 correspondingly comprises a second support shaft 18 to which the treatment elements 6 to 15 are rotationally conjointly attached. The treatment element shafts 4, 4 are each mounted so as to be rotatable about an axis of rotation 19, 19 oriented parallel to the conveying direction 5. The treatment element shafts 4, 4 can be driven in rotation by means of a drive motor 20. A distribution transmission 21 is arranged between the treatment element shafts 4, 4 and the drive motor 20, wherein a clutch 22 is arranged between the drive motor 20 and the distribution transmission 21. The treatment element shafts 4, 4 are driven in the same sense, that is to say in the same directions of rotation 23, 23, about the respective axis of rotation 19, 19.

(15) The housing 16 comprises housing sections 24, 25. On a first housing section 24 along the conveying direction 5, there is arranged a material feed 26 in the form of a funnel through which the plastics material 2 for preparation, and possibly the additives 3, can be introduced into the housing bores 17, 17.

(16) The screw machine 1 has, in series in the conveying direction 5, a drawing-in zone 27, a melting zone or plasticizing zone 28, a degassing zone 29, a homogenizing zone 30, a conveying zone and mixing zone 31, and a pressure build-up zone 32. The housing 16 comprises a nozzle plate 33 which is connected to the final housing section 24 in the conveying direction 5. The nozzle plate 33 has a discharge opening 34.

(17) The treatment elements 6, 6, 7, 7 10, 10, 12, 12, 13, 13, 14, 14, 15, 15 are in the form of screw elements. The treatment elements 8, 8, 9, 9, 11, 11 are in the form of kneading elements. The housing sections belonging to the treatment elements 6, 6, 7, 7 10, 10, 12, 12, 13, 13, 14, 14, 15, 15 in the form of screw elements are denoted by the reference designation 24. The housing sections denoted by the reference designation 25 interact with the treatment elements 8, 8, 9, 9, 11, 11 in the form of kneading elements.

(18) The kneading elements 8, 8, 9, 9, 11, 11 have kneading discs 48 which are arranged so as to be angularly offset with respect to one another and in series in the conveying direction 5. Multiple kneading discs 48 which are arranged adjacent to one another are formed as a single-piece kneading block.

(19) In the drawing-in zone 27, the screw elements 6, 6, 7, 7 are arranged on the respective support shafts 18, 18. Said screw elements 6, 6, 7, 7 engage into one another so as to be configured to sealingly mesh in pairwise fashion. In the melting zone 28, kneading elements 8, 8, 9, 9 are arranged on the support shafts 18, 18, which kneading elements are likewise configured to sealingly mesh in pairwise fashion. In the subsequent degassing zone 29, screw elements 10, 10 which sealingly mesh with one another are in turn arranged on the support shafts 18, 18. The housing section 24 belonging to the degassing zone 29 has a degassing opening 35 for the degassing of the plastics material 2 for treatment. In the subsequent homogenizing zone 30, kneading elements 11, 11 which sealingly mesh with one another are arranged on the support shafts 18, 18. Furthermore, in the subsequent conveying zone and mixing zone 31, screw elements 12, 12, 13, 13 which sealingly mesh with one another are arranged on the support shafts 18, 18. Correspondingly, in the subsequent pressure build-up zone 32, the screw elements 14, 14, 15, 15 are arranged on the support shafts 18, 18. The treatment elements 6 to 15, 6 to 15 are for example of single-start or two-start form.

(20) FIG. 3 illustrates the screw machine 1 in a cross section. The treatment elements 6 to 15, 6 to 15 each have a main body 36. The respective main body 36 is extended through by a shaft bore 37, 37. The shaft bores 37, 37 are in the form of hubs with a toothing. For the rotationally conjoint connection of the support shafts 18, 18 to the treatment elements 6 to 15, 6 to 15, the support shafts 18, 18 have a corresponding undulating profile which interacts in positively locking fashion with the hub profiles of the shaft bores 37, 37. The central longitudinal axes of the shaft bores 37, 37 coincide with the central longitudinal axes of the housing bores 17, 17 and the axes of rotation 19, 19. The shaft bore 37 is delimited by an inner wall 38. The main body 36 is furthermore delimited by connection walls 39 between two treatment elements 6 to 15, 6 to 15 which are adjacent along the conveying direction 5. The main body 36 is furthermore delimited by an outer wall 40. The outer wall 40 comes into contact with the plastics material 2 and is designed to act on the plastics material 2.

(21) The main body 36 has a length L.sub.W in the conveying direction 5. The shaft bore 37 extends in the conveying direction 5 through the entire main body 36, such that the shaft bore 37 also has the length L.sub.W. The treatment elements 6 to 15, 6 to 15 have the outer diameter D.sub.W. The housing bores 17, 17 have the diameter DG.

(22) The outer wall 40, both of the screw elements and of the kneading elements, comprises in each case one ridge section 41 and one base section 42. In the region of the ridge section 41, the outer wall 40 has the outer diameter D.sub.W. The base section 42 forms flanks 43 of the treatment elements 6 to 15, 6 to 15.

(23) FIG. 4 illustrates the screw element 6 in further detail. The outer wall 40 comprises multiple first wall sections W.sub.1 and multiple second wall sections W.sub.2. The first wall sections W.sub.1 are of strip-like form and run parallel to a helical line 44 of the screw element 6. Altogether, the outer wall 40 comprises two of the first wall sections W.sub.1. Both wall sections W.sub.1 are arranged in the ridge section 41. The second wall sections W.sub.2 form the remaining surface of the outer wall 40. The second wall sections W.sub.2 extend over the ridge section 21 and the base section 42.

(24) The first wall sections W.sub.1 have a dimension X.sub.1 perpendicular to their main extent direction and in the conveying direction 5. Along their main extent direction, the first wall sections W.sub.1 have a dimension L.sub.1 which corresponds to the length of the helical line 44. For the ratio L.sub.1/X.sub.1, the following applies: L.sub.1/X.sub.1?10. The first wall sections W.sub.1 are correspondingly of strip-like form.

(25) The first wall sections W.sub.1 project outwards in a radial direction, and perpendicularly with respect to the outer wall 40, beyond an envelope 45 spanned by the second wall sections W.sub.2. In particular, the first wall sections W.sub.1 are formed by deposition of material layers M.sub.1. The material layer M.sub.1 has a layer thickness D.sub.1 in a radial direction with respect to the respective axis of rotation 19, 19. Preferably, the layer thickness D.sub.1 is at least 1 mm and at most 4 mm.

(26) The application of the material layer M.sub.1 is performed for example by means of at least one of the following material deposition methods: laser welding, PTA welding (PTA: Plasma Transferred Arc), electrode welding, thermal spraying, hot isostatic pressing, sintering, brazing, additive manufacture, CVD coating (CVD: chemical vapor deposition) and/or PVD coating (PVD: physical vapor deposition), coating by detonation.

(27) To form the first wall sections W.sub.1, at least one material of the first material layer M.sub.1 is selected from the materials: cobalt-based alloys (Stellite), NiCrBSi-based alloys, powder metallurgical tool steels with or without a hard substance fraction and/or based on iron, composite materials composed of at least one of the above-stated materials, preferably with additional carbidic and/or nitridic hard substance inclusions, CrN, TiAlN, TiC.

(28) The second wall sections W.sub.2 are formed by a base material M.sub.2 of the main body 36. The second wall sections W.sub.2 have a layer thickness D.sub.2. The base material M.sub.2 is a conventional base material, such as for example the steel material M.sub.2. In particular, the material layer M.sub.1 is harder than the base material M.sub.2. In this way, it is ensured that the first wall section W.sub.1 is harder than the second wall section W.sub.2. In particular, the first wall section W.sub.1 is harder by 100 HV 10 than the second wall section W.sub.2.

(29) The outer wall 40 has a profiling 46. The profiling 46 is formed by virtue of the first wall sections W.sub.1 projecting, in a radial direction with respect to the axis of rotation 19, beyond the envelope 45 spanned by the second wall sections W.sub.2. In the region of the ridge section 41, the first wall sections W.sub.1 thus deviate from the second wall sections W.sub.2 in a radial direction with respect to the axis of rotation 19. The first wall sections W.sub.1 form webs, between which a channel in the form of the second wall section W.sub.2 extends. In this way, an improved conveying and sealing action can be attained.

(30) Only the first wall section W.sub.1 lies on a lateral surface of revolution 47 of the main body 36. The lateral surface of revolution 47 is defined by the outer envelope spanned in the case of the complete rotation of the respective treatment element 6 to 15, 6 to 15 about the axis of rotation 19, 19.

(31) A screw element according to a further exemplary embodiment will be described on the basis of FIG. 6 and FIG. 7. By contrast to the exemplary embodiment described above, the first wall sections W.sub.1 arranged on the ridge section 41 are oriented parallel to the axis of rotation 19. The ratio L.sub.1/X.sub.1 is at least 0.5 and at most 10. The first wall sections W.sub.1 are in turn arranged exclusively on the ridge section 41, and the second wall sections W.sub.2 are formed on the ridge section 41 and on the base section 42.

(32) The first wall sections W.sub.1 do not project beyond the envelope 45 spanned by the second wall sections W.sub.2. Rather, the first wall sections W.sub.1 lie on the envelope 45. The second wall sections W.sub.2 arranged in the ridge section 41 are oriented parallel to the first wall sections W.sub.1. The outer wall 40, in particular the ridge section 41, has no profiling.

(33) The first material layer M.sub.1 is formed by hardening of the base material M.sub.2. The hardening of the material layer M.sub.1 is performed for example by means of at least one of the following hardening methods: case hardening, nitriding, boriding, laser hardening.

(34) A further exemplary embodiment will be described on the basis of FIG. 8 and FIG. 9. By contrast to the exemplary embodiments described above, the treatment element 6 to 15, 6 to 15 formed with the first wall sections W.sub.1 and the second wall sections W.sub.2 is a kneading element 8, 8, 9, 9, 11, 11. The kneading element 8 comprises third wall sections W.sub.3 in addition to the first wall sections W.sub.1 and the second wall sections W.sub.2. The wall sections W.sub.1, W.sub.2, W.sub.3 are of strip-like form. A main extent direction of the wall sections W.sub.1, W.sub.2, W.sub.3 is oriented obliquely with respect to the axis of rotation 19 and obliquely with respect to a cross-sectional area of the kneading element 8. The wall sections W.sub.1, W.sub.2, W.sub.3 extend in each case over the ridge section 41 and the base section 42.

(35) The third wall sections W.sub.3 have a material layer M.sub.3, the hardness of which is lower than that of the base material M.sub.2.

(36) A further exemplary embodiment of a treatment element 6 to 15, 6 to 15 will be described on the basis of FIG. 10 and FIG. 11 using the example of the kneading element 9. By contrast to the exemplary embodiments described above, a ratio between the dimension L.sub.1 of the respective first wall section W.sub.1 along the axis of rotation 19 and the dimension X.sub.1 of the respective first wall section W.sub.1 perpendicular to the dimension L.sub.1 parallel to the outer wall 40 is at most 5. In particular, the dimension of the first wall sections W.sub.1 is smaller than a length Lx of a kneading disc 48 along the conveying direction 5. The second wall section W.sub.2 is of lattice-like form. At least some of the first wall sections W.sub.1 are completely surrounded by the second wall section W.sub.2. The first wall sections W.sub.1 project, in a radial direction with respect to the axis of rotation 19, beyond the envelope 45 spanned by the second wall section W.sub.2. The lateral surface of revolution 47 is spanned only by the first wall sections W.sub.1.

(37) In general, the formation of the at least one first wall section W.sub.1 and of the at least one second wall section W.sub.2 may be performed by treatment of the outer wall 40 in a hardening process, in particular by thermal hardening, and/or by material deposition. The at least one first wall section W.sub.1 and the at least one second wall section W.sub.2 are in contact, during the operation of the screw machine, with the plastics material 2 for treatment. The layer thickness D.sub.1 may be less than, equal to or greater than a layer thickness D.sub.2 of the second wall section W.sub.2. The layer thickness D.sub.2 is preferably greater than the layer thickness D.sub.1. The material layers M.sub.1, M.sub.2 may be treated or processed after the deposition. The several first wall sections W.sub.1 and/or the several second wall sections W.sub.2 may be of identical and/or different form with regard to their geometry and/or hardness and/or material composition.