GB2200570A

GB2200570A - Kneader-mixer

Info

Publication number: GB2200570A
Application number: GB08729015A
Authority: GB
Inventors: Heinz List
Original assignee: List AG
Current assignee: List AG
Priority date: 1986-12-12
Filing date: 1987-12-11
Publication date: 1988-08-10
Anticipated expiration: 2007-12-11
Also published as: JPS63197526A; CH674471A5; SE8704945D0; GB2200570B; SE8704945L; GB8729015D0; DE3704268A1

Abstract

A kneader-mixer for performing mechanical and thermal processes with flowable and/or viscous-pasty products, comprises a heatable and coolable casing (3) with a jacket (10), and heatable and coolable kneading stirrer equiaxially revolving with the casing axis, the mixing and kneading action being achieved with oppositely moved kneading tools, which on the one hand are constructed as radial, axially distributed disk elements (16, 17) and on the other as counter tools between the radial planes of the disk elements, and to which between the disk surfaces of the disk elements are arranged at least one pair of kneading elements (30, 33) which form radial kneading gaps with the disk elements in which the product is subject to powerful shearing forces, transport bars (36) revolving with the stirrer being provided for the axial transport of the product through the apparatus. <IMAGE>

Description

KNEADER-MIXER WITH RADIAL KNEADING GAPS The invention relates to a kneader-mixer for performing mechanical and thermal processes with flowable and/or.

viscous-pasty products.

The prior art, such as German patent 2349106 or Swiss patent 410789, discloses kneader-mixers, in which radial disk elements are fixed to a kneader shaft, the disk elements being cleaned by kneading counter elements fixed in the casing. The kneading elements fixed in the -casing according to German patent 2349106 have a hook shape and between the first part of the kneading hook approximately parallel to the casing inner wall and the counter elements, an axial kneading gap is formed through which the product is pressed with the aid of transport and kneading bars approximately axially fixed to the outer diameter of the disk elements so as to obtain a kneading action.Thus, the kneading gap only has an effect if the axial transport bars on the disks pass through the kneading gap, ie as a function of the number of the kneading bars three to four times per revolution. The radial parts, kneading hooks and the hook part engaging on the shaft which are parallel to the disks contribute little to the actual kneading action and only clean the disk elements. In this prior art, the kneading action is mainly limited to the axial kneading gaps and even there only to the short time taken by the kneading bars to pass through the kneading gap.

In Swiss patent 410789 the kneading action of the radial kneading pins is substantially negligible, because it is mainly a question of cleaning tools for the disk surfaces and as a result of the reciprocating movement of the kneading shaft, the radial pins only engage with the disk surface for a short time.

According to the present invention, there is provided a kneader-mixer for performing mechanical and thermal processes with flowable and/or viscous-pasty products, with a heatable and coolable casing and heatable and coolable kneading stirrers disposed at axial intervals along the casing and rotatable coaxially with the casing on a stirring shaft, the rising and kneading action being obtained by oppositely moved kneading tools, which comprises radial, axially distributed disk elements and counter tools between the radial planes of the disk elements, wherein the counter tools between the disk surfaces of the disk elements each comprise at least one first kneading element taking the product from the first disk surface and guiding it into a radial kneading gap, which comprises a kneading surface of the kneading element gradually becoming parallel to the opposite second disk surface and at least one second kneading element which follows the first kneading element and which takes up the product passing out of the first radial kneading gap and passes it into a radial kneading gap between the kneading surface of the second kneading element and the first disk surface, and wherein for the axial transport of the product through the apparatus either the kneading tools rotating with the stirring shaft are provided with suitable transport bars or separate transport elements are fixed to the stirring shaft.

The present invention counteracts the disadvantage of the limited kneading effect of the only briefly acting kneading gaps in the aforementioned citation through a special construction of a successively arranged pair of kneading elements, because the product is intensely worked for a longer distance per kneading shaft revolution also in the radial kneading gaps along the disk surfaces.

This principle can be realised in two different movement modes. In one case the disks are fixed in the casing, whilst the kneading elements revolve with the shaft between the disks. In the other case the disk elements revolve with the shaft, whilst the kneading elements are fixed in the casing.

The invention is described in greater detail hereinafter by way of non-limitative example with reference to the accompanying drawings, in which: Fig 1 is an overall view of an embodiment of a kneadermixer according to the present invention for continuous operation with a casing partly cut open along line I-II in fig 2.

Fig 2 is a cross-section along line III-IV of the kneader-mixer of fig 1.

Fig 3 is a detail of the lower half of the kneadermixer of fig 2, sectioned along circular line V-VI.

Fig 4 is a cross-section along line III-IV of fig 1 with the stirrer position necessary for removing the casing.

Fig 5 shows kneading elements with relief slots in the kneading surfaces.

Fig 6 is a cross-section through a kneader-mixer with a transport bar mounted on a kneading element and vertically arranged semicircular-anru'lar disks.

Fig 7 shows the lower half of the cross-section of fig 6, sectioned along line VII-VIII of fig 6.

Fig 8 shows a development similar to fig 7, but with an elastic construction of the kneading surfaces on the kneading elements.

Fig 9 is a partial longitudinal section through a kneader-mixer with separate transport bars and axial kneading gap.

Fig 10 is a plan view of the transport bars.

Fig 11 is an overall view of a kneader-mixer with three flanged casing parts and an outlet casing.

Fig 12 is a cross-section through the inlet casing along line IX-X of fig 11 with the stirrer position.

Fig 13 is a cross-section along line XI-XII of the central casing part of the kneader-mixer of fig 11.

Fig 14 is a cross-section through the casing outlet part along line XIII-XIV of the kneader-mixer of fig 11.

Fig 15 is a cross-section through a kneader-mixer similar to fig 1, but with a second transport bar for the return of the product.

Fig 16 is an overall view of a batchwise-operating kneader-mixer with rotary disks and kneading elements fixed in the casing with a part longitudinal section along line XV-XVI in fig 17.

Fig 17 is a cross-section along line XIX-XX of the kneader-mixer of fig 16.

Fig 18 is a view of a continuously operating kneadermixer similar to fig 1, but with an additional oscillating movement of the kneading shaft.

Figs 1, 2 and 3 show the construction of a continuously operating kneader-mixer, in which the disk elements are fixed in the casing and the kneading and transport elements revolve with the stirring shaft. The working area is longitudinally subdivided into casings 1, 2 and 3 as well as the outlet casing 4, which is screwed together with flanges 5. The outer flanges 6 and 7 are joined to the end walls of the casing, in which the stuffing boxes 8 and 9 are arranged. As can be gathered from the longitudinal section of casing 3 in fig 1, all the casing parts are provided with heating jackets 10, whose connections are not shown so as not to overburden the drawing. It is also possible to see inlet connection 11, outlet connection 12, a vapour removal connection 13, an observation opening 14 and the drain connections 15 for the different casing parts.

The annular segment-shaped disk elements fixed to the casing are distributed at regular intervals over the entire kneader-mixer length. Two disk elements 16, 17 are provided in each disk plane and leave between them an axial passage 18 free in the lower part. The disk elements are partly welded into the casing or are fixed between the flanges 5.

The disk 19 fixed between casing part 3 and outlet casing 4 is, however, constructed as a baffle plate without any axial passage. The upper overflow edge of said baffle plate 19 serves to maintain a specific filling level in the kneadermixer.

The stirrer comprises the central. pipe 20 into both sides of which are welded the shaft journals 21, 22. The shaft journals are mounted in bearing boxes 25, 26 of cages 23, 24. The shaft is driven by an electric motor (not shown) via a V-belt pulley 27 and reduction gear 28.

Sealing head 29 verves to supply and remove the heating medium for heating the stirring shaft and kneading elements.

In the outlet casing 4 the stirrer is provided with a frame-like stirring element 38, which cleans the outlet casing and moves the product into the outlet connection 12.

Fig 3 is a development of the lower casing half in a plane, all parts being sectioned on a circular line V-VI of fig 2. Between the heated disk surfaces defined by pairs of the disk elements 16 and 17 there is provided a kneading element pair welded to the stirrer with kneading blades 30 and 33, each of which comprises a supply part 31 or 34 and a kneading surface in kneading gap 32 and 35. To the revolving stirring shaft are also fixed the transport elements 36 with the transport bars 37 which, by being inclined in the manner df a helix, transport the product from the inlet connection 11 to the outlet part through the passages 18 in the disk planes The products are fed in dosed manner into the inlet connection 11 for performing the process. They pass through the apparatus and are thermally treated by heating.In many processes, as a result of the thorough mixing of the product in the entry zone and through the supply of heat, a viscouspasty phase is very rapidly obtained and this subsequently passes into a flowable state by the evaporation of a volatile substance.

The end product passes over the baffle plate 19 into the discharge head 4, where it is discharged. During the viscous-pasty phase, the product must undergo thorough working, ie a very intense kneading process. This is achieved by the nature of the kneading elements and can best be gathered from fig 3. The successively connected kneading elements 30 and 33 in each case form a pair. Considered in the rotational direction, the first kneading element 30 with the scraping edge 31 deflects the product from the first disk surface and passes it into a kneading gap formed by the second disk surface and passes it into a kneading gap formed by the second disk surface of the opposite disk element and the kneading surface 32 of kneading element 30. The viscous product is subject to powerful shearing forces in said radial kneading gap in known manner.The product passing out of the kneading gap is taken up by the facing disk by means of the scraping part 34 of the following kneading element 33 and is passed into the second kneading gap, which is formed by kneading surface 35 and the aforementioned first disk surface. This process covers substantially the entire material which, within the area between two disk surfaces, is subject to a powerful transport movement from one disk surface to the other and is exposed to the strong shearing forces in the two kneading gaps. Any vapours of gases which have evolved are removed by connections 13.

During the process the product is transported through the machine by transport bars 36, 37. The end product is taken up in the outlet casing and by means of stirring element 38 is discharged through the outlet connection 12. If the product is in the viscous-pasty state there, special extrusion elements are incorporated.

The cross-section of fig 4 corresponds to the crosssection of fig 2, but has a different stirrer position, which permits simple removal of the casing for cleaning purposes. The kneading elements 30 and 33 are located in the free cross-section above disk elements 16 and 17, whilst the transport element 36, 37 is placed in the passage 18 between the two disk elements 16 and 17. The casing can be removed without difficulty in this position.

Certain products have a marked compression tendency in the kneading gap, particularly on passing from the viscouspasty to the free-flowing phase. With respect to such products, strip-like relief slots in the kneading surface have proved to be advantageous, as shown in fig 5. In the kneading element 40 said slots are arranged on circular paths, whilst kneading element 41 shows a construction with slots inclined with respect to the circular path.

In figs 6 and 7 a bar 43 is fixed as the transportation element on the outer diameter of kneading element 42. This transportatn element passes with a limited spacing along the inner wall of the casing and transports the material axially forwards as a result of its angular position. The following second kneading element 44 of the kneading element pair has in this example no transport bar. In the disk plane is provided a single disk element 45 in the form of a vertical, half-circular disk. Directional arrows 46 indicate the movement of the kneading elements between disks 45, whilst arrow 47 shows the axial displacement of the product. This arrangement of the transport bars permits the housing of several kneading element pairs within two disk surfaces, or an additional transport element for the return of the product.The kneading elements 50 and 5 according to fig 8 have an elastic construction of the kneading surfaces 51, 53, so that the kneading pressure is automatically adjusted within certain limits.

The action of the radial kneading gaps within the disk surfaces can, according to the longitudinal section of fig 9, be increased by the construction of an axial kneading gap 54 between the internal diameter of casing 55 and the external diameter of the kneading elements. For this purpose the radial spacing between the external diameter of kneading element 56 and the inside of casing 55 is increased and the outer edges of kneading element 56 are bevelled in such a way that a conical kneading gap is obtained. This longitudinal sectional detail also shows the transport bars 36, 37.

The different constructions of the disk elements and also the kneading elements can be combined in a wide variety of ways. There are also various possible combinations as regards the materials. For certain products it has also proved advantageous to coat the kneading elements with plastic, or to adopt a construction of plastic only, particularly to the reduction of the friction coefficient between the kneading elements and the product.

In the case of several kneading element pairs in the space between two disk surfaces, the scraping edges can also be toothed. This tooth system must be constructed in such a way that it is superimposed with the tooth system of the scraping edges on the other kneading elements, so that the entire surface area is scraped.

Fig 11 with the cross-sections of figs 12, 13 and 14 shows a three-part arrangement of the flanged casing parts 60, 61, 62 with an also flanged outlet casing 63.

For complete cleaning, initially the outlet casing 63 with cage 64 is removed and subsequently the stirrer is brought into a position corresponding to fig 12. In this position firstly the casing 62 is removed and then the stirrer is so rotated by approximately 120O leads to a uniform loading of the drive.

For various processes a return of part of the product from the outlet to the inlet has proved advantageous. This function can be achieved through the incorporation of several transport elements, whereof at least one is so inclined that the material is conveyed rearwards, ie int he direction of the inlet connection. In fig 15 the disk elements correspond to the construction of fig 2. In addition to the kneading elements 16, 17 and the transport bars 36, 37, transport bars 65, 66 are provided for return purposes. The returned product quantity can be regulated by a corresponding choice of the gradient on transport element 66. The product can also be greatly improved by the inclination of the apparatus. For this purpose the apparatus is inclined in such a way that the product must overcome a gradient from the inlet connection to the outlet connection.However, a better emptying of the machine is made possible by a downward slope of the outlet connection.

The machine shown in fig 16 has a basically different kneading principle, in which the disk element 70 heated in a batchwise-operating apparatus are fixed to the kneading shaft 71 and revolve therewith. The transport bars 72 are fixed to the external diameter of the disk elements. Fig 17 shows the cross-section with respect to this machine. The kneading elements 73, 74 are fixed in flange covers in casing 75. A gap is laterally formed alongside supports 76, 77 for the kneading blades between the inner wall of casing 75 and the external diameter of kneading elements 73, 74 and through it pass the transport bars 72 and bring about an axial kneading action in the axial kneading gap, in addition to the kneading action in the radial kneading gaps.The cylindrical casing 75 is provided with a heating jacket 78 and flanges, to which the end plates with the stuffing boxes and bearing cages with the bearings are flanged.

For uniform loading of the drive by the shearing forces, here again the kneading elements in the various casing parts are arranged with different angular positions.

The transport bars are adjusted in such a way that in the outer casings there is a transport from the outer end walls to the centre. The material transported to the centre is conveyed back to the end walls in the upper part of the machine. A good product interchange in the container is brought about through this circulation.

The construction of another continuous machine similar to fig 1 is shown in fig 18. This kneader-mixer has the special feature that there is an axial oscillation in addition to the rotation of the kneading shaft. The axial oscillation is brought about by means of two hydraulically operated piston drives 80, 81 and by means of a bridge is transmitted to the kneader shaft 83 independently of its rotation. To be able to move the shaft, it is necessary to make the axial, outer boundaries 84 of the kneading elements smaller by the necessary amount than the spacing between the disk planes. The advantage of such an arrangement is a greater material movement and a simple adaptation of the kneading intensity to the product and process. As regards the other parts, this construction corresponds to that described relative to fig 1. The drive with electric motor 86, the V-belt drive 87 and reduction gear 88 is so mounted in overhung manner on the shaft that it participates in the oscillation.

As a function of the particular requirements, all surfaces coming into contact with the product, including the kneading elements, can be heatable and coolable.

Claims

1. A kneader-mixer for performing mechanical and thermal processes with flowable and/or viscous-pasty products, with a heatable and coolable casing and heatable and coolable kneading stirrers disposed at axial intervals along the casing and rotatable coaxially with the casing on a stirring shaft, the rising and kneading action being obtained by oppositely moved kneading tools, which comprises radial, axially distributed disk elements and counter tools between the radial planes of the disk elements, wherein the counter tools between the disk surfaces of the disk elements each comprise at least one first kneading element taking the product from the first disk surface and guiding it into a radial kneading gap, which comprises a kneading surface of the kneading element gradually becoming parallel to the opposite second disk surface and at least one second kneading element which follows the first kneading element and which takes up the product passing out of the first radial kneading gap and passes it into a radial kneading gap between the kneading surface of the second kneading element and the first disk surface, and wherein for the axial transport of the product through the apparatus either the kneading tools rotating with the stirring shaft are provided with suitable transport bars or separate transport elements are fixed to the stirring shaft.

2. A kneader-mixer according to claim 1, wherein the leading edges of the kneading elements are constructed as scraping edges, which move very closely past the disk surfaces.

3. A kneader-mixer according to claims 1 or 2, wherein the disks are fixed in the cylindrical casing and the kneading elements to the stirring shaft stirrer.

4. A kneader-mixer according to any one of claims 1 to 3, wherein at least the kneading surfaces of the kneading elements are strip-like or have other passage openings for relieving the kneading pressure in the kneading gap.

5. A kneader-mixer according to any one of claims 1 to 4, wherein the kneading space between two disk surfaces, there are several kneading element pairs, which supplement one another with regard to covering the kneading surfaces and/or the scraping edges.

6. A kneader-mixer according to any one of claims 1 to 5, wherein at least parts of the kneading elements are made or coated with plastic.

7. A kneader-mixer according to any one of claims 1 to 6, wherein the kneading surfaces of the kneading elements are elastic.

8. A kneader-mixer according to any one of claims 1 to 7, wherein in each case at least one kneading element between two disk surfaces is provided at its periphery with an axially extending transport bar inclined with respect to the axial surface line of the casing.

9. A kneader-mixer according to any one of claims 1 to 8, wherein an axial kneading gap is formed by a wedge-like construction of the kneading elements on the external diameter, in addition to the radial kneading gaps between the cylindrical casing and the kneading elements.

10. A kneader-mixer according to anyone of claims 1 to 9, wherein in one disk plane two disk elements are provided, between which at the bottom there is a passage for the axial transport of the product and at the top a passage for removing gages.

11. A kneader-mixer according to claim 10, wherein the disk elements with the passage are superimposed, so that the other half of the casing cross-section is free for the axial passage of product and gases.

12. A kneader-mixer according to anyone of claims 1 to 9, wherein the disk elements are constructed as half-closd circular disks in the lower half of the casing cross-section with a passage opening in the lower region.

13. A kneadar-mixer according to any one of claims 1 to 12, wherein the openings in the disk planes are arranged in such a way that in each case one casing part can be removed without being impeded by the kneading and transporting elements located on the stirrer shaft.

14. A kneader-mixer according to any one of claims 1 to 13, wherein the casing comprises several detachably flanged casing parts and in each casing part the kneading elements are arranged in different angular position to provided for a uniform force distribution.

15. A kneader-mixer according to claim 1, wherein disks are fixed to the stirring shaft and revolve therewith and the kneading elements are so fixed to short supports in the cylindrical casing that on either side of the narrow support between the inner wall of the casing and the kneading elements there is formed an axial kneading gap, through which the product is pressed by the axially positioned transport bars which are fixed to the external diameter of the disks.

16. A kneader-mixer according to claim 1, wherein in addition to the transport elements for transport from the inlet to the outlet, there are also transport elements in the opposite direction for the partial return of the product.

17. A kneader-mixer according to claims 1 and 15, wherein the longitudinal axis thereof is inclined or inclinable.

18. A kneader-mixer according to anyone of claims 1 to 17, wherein the stirring shaft with the kneading elements and transport bars, are arranged to an axial, oscillating movement up to approximately half the axial spacing between the disk surfaces, the axial boundary of the kneading element pairs being chosen in such a way that said axial movement is possible.

19. A kneader-mixer constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.