DE29723087U1 - Compounder for plasticizable materials - Google Patents

Description

21 January 1998
SI/cs95197G

Compounder for plasticizable masses

The invention relates to a compounder for plasticizable masses with at least two parallel shafts that rotate in the same direction and are divided into at least three axial sections, whereby processing elements with a first radius are arranged in a first section and processing elements with a radius that differs from the first radius are arranged in a second section, and whereby the shafts are housed with a constant axial distance in a housing with chambers that merge into one another and have a correspondingly adapted inner diameter. In this context, the radius of the processing elements is understood to mean the distance between the axis of rotation and a vertex of the respective element.

Compounders of the type mentioned above can be used to knead and mix plasticizable masses in order to be able to process them further. For this purpose, the masses required for mixing can be introduced into the housing at various axially spaced feed points according to the progress of the kneading and mixing process.

A compounder of the type mentioned above that can be used for this purpose is known from EP 0 087,699 Al. In the known compounders, the individual processing elements are made up of different axial sections that differ not only in their radius,

but also differ from each other in that they are designed as single- or multi-threaded screw elements or as essentially disc-shaped mixing and kneading elements.

In the known compounder, the radius of the processing elements in the initial section of the conveyor line is smaller than in the second section that follows. In this way, in the first section, for example, additives can be intensively mixed into a base mass using a high kneading power. In the following section with a larger radius, other substances can be gently mixed in using less force.

The well-known compounder allows materials to be mixed in using different forces. The disadvantage, however, is that the diameter of the processing elements and the chambers in the pull-out direction can only increase in order to enable the shafts to be pulled out of the housing. For this reason, optimal working conditions cannot be created for a large number of processing operations with the well-known compounders.

The invention is based on the object of creating a compounder of the type mentioned at the beginning, which, with a simple structure and high efficiency, enables processing that is better adapted to the required processing steps.

This task is solved by the machining elements in the first section having a two-start profile and in the second section following the first section having at least a three-start profile.

profile and in the third section following the second section a two-start profile and that the radius of the machining elements in the first section and in the third section is larger than the radius of the machining elements in the second section.

The invention makes it possible to create a multi-stage compounder with a constant center distance of the shafts and a simple structure of the compounder, in which in a first section with a large radius of the processing elements, a gentle incorporation of additives into a base mass is possible using gentle force. In the second section, intensive kneading and mixing takes place with a reduced diameter. In the last section, with a larger diameter and thus lower forces acting on the mass, for example, degassing and/or further additives are mixed in.

The constant distance between the shafts is achieved by a suitable combination of the profiles of the processing elements selected for the large diameter area and the small diameter area. By using a two-start profile in the large diameter sections, the materials are worked into this area with gentle kneading and conveying work. At the same time, the desired self-cleaning of the elements is maintained. In the area of the reduced diameter, the use of at least three-start elements can be aligned in such a way that self-cleaning and the desired high kneading performance are ensured with a constant shaft distance.

A compounder according to the invention, with which the processing steps "mixing", "intensive kneading and mixing", "degassing" can be carried out particularly effectively, is characterized in that the processing elements in the first section are designed as conveyor screws and in the second section as mixing and kneading elements.

A practical embodiment of the invention is also characterized in that the housing is divided into several housing sections assigned to the sections of the shafts and that at least the housing sections with the smallest chambers in terms of internal diameter can be opened up perpendicular to the axial direction. Due to the division of the housing sections with the smallest chambers, these housing sections can be opened up so far for pulling the shafts in the axial direction that shafts with alternating large and small diameters can also be pulled out.

The compounder according to the invention also allows for the use of changing shafts, whereby the housing sections in the inner diameter of the smallest chamber must correspond to the diameter of the shaft to be used. In any case, the compounder according to the invention offers significantly greater freedom in the choice of shaft equipment compared to conventional compounders, which allows for optimal adaptation to the changing needs when plasticizing and mixing plasticizable materials.

According to one embodiment of the invention, each division plane lies in a radial plane of the adjacent shaft. This geometry benefits the easy opening of the housing sections.

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According to a further embodiment of the invention, the inner diameter of the chamber associated with the shaft section with the smallest diameter should be larger than the diameter of this shaft section and smaller than the diameters of the other shaft sections. With this embodiment, the compounder can be equipped with processing elements whose smallest diameter sections have different diameters without it being necessary to replace the movable parts of the housing section. It is accepted that, depending on the shaft section used, the play between the periphery of the shaft section with the smallest diameter and the inner diameter of the associated chamber is more or less large.

In order to be able to build up pressure in the axial direction of the compounder, the inner diameter of the chamber assigned to the shaft section with the smallest diameter can be reduced in the axial direction. In particular, it is provided that the inner diameter decreases from an inner diameter corresponding to the larger diameter of the other shaft sections, in particular the adjacent shaft section, to a smallest inner diameter corresponding to the diameter of the shaft section with the smallest diameter.

The invention is explained in more detail below using a drawing showing an embodiment. In detail:

Fig. 1 a compounder in the area of a smallest chamber diameter in cross section,

Fig. 2 the compounder according to Fig. 1 in a longitudinal section,

Fig. 3a the compounder according to Fig. 1 in a section along the line A-A of Fig. 1,

Fig. 3b the compounder according to Figs. 1 and 2 in a section along the line B-B of Fig. 1,

Fig. 4 shows a compounder in a modified version compared to Fig. 1 and 2 in the area of a housing section with the smallest chamber diameter and adjacent housing sections in axial section.

A compounder consists of several housing sections 1, 2, 3 arranged axially one behind the other. Each housing section 1, 2, 3 comprises a chamber 21, 22, 23. The axes AA of the chambers 21, 22, 23 arranged one behind the other or of the shafts 4, 5 arranged in them are parallel to one another.

The shafts 4, 5 rotate in the same direction and are divided into axial sections 4a, 4b, 4c. The first section 4a is assigned to a filling opening E, while the third section 4c is assigned to a gas outlet opening G.

In the first section 4a of the shafts 4,5, processing elements 40 designed as two-start screws are arranged, the apex of which is described by a radius Rl. In the following section 4b, directly adjacent to section 4a, five-start screw elements 41 are arranged as processing elements and, following them in the conveying direction F, mixing and kneading elements 42. The radius R2 of the screw elements 41 and the mixing and kneading elements 42

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is smaller than the radius Rl. In the third and last section 4c, two-start worm-shaped processing elements 43 are arranged, the radius R3 of which is equal to the radius Rl of the processing elements 40. In all sections 4a to 4c, the respective processing elements 40-43 have a shape of a self-cleaning Erdmenger profile adapted to the respective number of starts.

In section 4a, additives can be added to a base mass via the filling opening E. These components are gently mixed together in section 4a due to the large radius Rl of the processing elements 40 and the associated large inner diameter of the chamber 21. In section 4b, the components are then intensively mixed and kneaded together. Gases generated in this process can escape from the mass in area 4c, where it is further conveyed with less force due to the larger inner diameter of the chamber 23 and the larger radius R3 of the processing elements 43.

The individual housing sections 1, 2, 3 are held together by screwed-together flanges 6, 7. As can be seen from Fig. 1, the middle housing section 2 with the smallest inner diameter is axially divided several times. The chambers 22 are formed by parts 8, 9, 10, 11, which can be opened perpendicular to the axial direction. The drawing shows both their operating position (8), (9), (10), (11) and their opened position 8, 9, 10, 11. The division planes 8a, 8b, 9a, 9b, 10a, 10b, 11a, 11b lie in the radial planes of the adjacent shafts 4, 5.

In Fig. 1, a dotted line indicates that behind the sections 4b of the shafts with

4, 5 with the smallest diameter are sections 4a with a larger diameter. These sections 4a and 4c can also be pulled out to the front (out of the plane of the drawing) with the housing section extended with parts 8 to 11, because the cross-section in the area of the chamber with the smallest diameter is freed up for this.

If the compounder is to be fitted with a different shaft, e.g. with a shaft that has a larger diameter in the area of the housing section with the smallest diameter, it is necessary to replace parts 8 to 11 with parts with a correspondingly larger diameter.

The embodiment of Fig. 4 differs from that of Figs. 1 to 3b only in that the chamber 21 is not circular-cylindrical, but conical. Its largest diameter corresponds to the inner diameter of the adjacent chamber with the larger diameter shaft section 4c, while its smallest inner diameter corresponds to the diameter of the shaft section 4b.

It goes without saying that not only the housing section with the smallest diameter can be divided into individual, removable parts, but also other housing sections. The more housing sections are divided into removable parts, the greater the freedom in refitting.

Claims (5)

—1~ 21 January 1998
SI/cs95197G EXPECTATIONS Compounder for plasticizable masses with at least two parallel shafts (4, 5) rotating in the same direction, which are divided into at least three axial sections (4a, 4b, 4c), wherein in a first section (4a) processing elements (40) with a first radius (Rl) and in a second section (4b) processing elements (41) with a radius (R2) different from the first radius (Rl) are arranged, and wherein the shafts (4, 5) are housed at a constant axial distance in a housing with chambers (21, 22, 23) merging into one another with a correspondingly adapted inner diameter, characterized in that the processing elements (40) in the first section (4a) have a two-start profile, in the second section (4b) following the first section (4a) an at least three-start profile and in the third section (4c) following the second section (4b) a have a two-start profile and that the radius (Rl, R3) of the machining elements (40) in the first section (4a) and in the third section (4c) is larger than the radius (R2) of the machining elements (41, 42) in the second section (4b). 2. Compounder according to claim 1, characterized in that the processing elements (41, 42) ^are designed as conveyor screws in the first section (4a) and as mixing and kneading elements in the second section (4b). 3. Compounder according to one of the preceding claims, characterized in that the housing is divided into several housing sections assigned to the sections (4a-4c) of the shafts (4, 5) and that at least the housing sections (2) with the smallest chambers (22) in terms of internal diameter can be opened perpendicular to the axial direction. 4. Compounder according to claim 3, characterized in that each parting plane (8a, 8b, 9a, 9b, 10a, 10b, 11a, lib) lies in a radial plane of the adjacent shaft (4, 5). 5. Compounder according to claim 3 or 4, characterized in that the inner diameter of the chamber (21) associated with the shaft section (4b) with the smallest diameter is larger than the diameter of this shaft section (4b) and smaller than the diameter of the other shaft sections (4a, 4c). β. Compounder according to one of claims 3 to 5, characterized in that the inner diameter of the chamber (21) associated with the shaft section (4b) with the smallest diameter decreases in the axial direction. Compounder according to claim 6, characterized in that the inner diameter of the chamber (21) of the shaft section (4b) with the smallest diameter is reduced from the inner diameter of the chambers of the other shaft sections (4a, 4c) with a larger diameter, in particular of the adjacent shaft section (4c), to an inner diameter which corresponds to the diameter of the shaft section (4b) in this chamber (21).