Patent Publication Number: US-3880407-A

Title: Mixer and kneader with counteractive blades

Description:
United States Patent 1 List [ 1 Apr. 29, 1975 1 MIXER AND KNEADER WITH COUNTERACTIVE BLADES [76] Inventor: Heinz List, St. .lakobsstrasse 43,  
 Pratteln, Switzerland [22] Filed: Oct. 17, 1973 [21] Appl. No: 407,040  
 [56] References Cited UNITED STATES PATENTS 3,279,894 10/1966 Tate 259/9 3,617,225 11/1971 Kuehnc..... 23/285 3,730,486 5/1973 Kondo 259/6 3,734,471 5/1973 Engels 259/10 Primary Exuminer-Robert W. Jenkins Attorney, Agent, or FirmToren, McGeady and Stanger 57 ABSTRACT In a mixer and kneader, an axially extending agitator rotates within a stationary cylindrically-shaped housing. In a number of axially spaced radially extending planes within the housing, plate-like elements are fixed to the agitator and are closely spaced inwardly from the inner surface of the housing. Each plane has a number of circumferentially spaced plate-like elements and each element has an axially extending stirrer blade attached to its radially outer edge. Between each adjacent pair of planes of the plate-like elements, a counter element is provided consisting of a support mounting attached to the inner wall of the housing and an axially extending counter blade secured to the radially inner surface of the support mounting. The stirrer blades are arranged to pass between the cylindrical housing and the counter blades affording a kneading action. Further, the stirrer blades afford a scraping action on the inner surface of the cylindrical housing while the counter blades afford a similar scraping action on the plate-like elements and the surface of the agitator. The counter blades can be formed in a frame-like configuration to provide additional kneading action.  
 18 Claims, 7 Drawing Figures PATENTEDAPRZSIQYS SHEET 3 BF 3 Fig. 7  
 MIXER AND KNEADER WITH COUNTERACTIVE BLADES SUMMARY OF THE INVENTION The present invention is directed to a mixer and kneader and. more particularly. it is directed to the arrangement of counteracting blades so that materials can be thoroughly mixed and kneaded.  
  The mixer and kneader of the present invention uses counteracting blades for the mechanical. chemical and thermal treatment of liquid. pasty and pulverulent products, with or without the input or output of gases and vapors. so that a satisfactory exchange of material is achieved in all phases. The mixer and kneader is formed of a rotatable agitator mounted within a stationary. cylindrically-shaped housing. In a number of axially spaced radially extending planes within the housing. a plurality of plate-like elements are secured to the agitator and extend outwardly to a point closely spaced from the inner surface of the housing. A stirrer blade is fixed to the radially outer edge of each of the plate-like elements and the blade extends in the axial direction. Positioned between each pair of adjacent planes of plate-like elements is a stationary counter element secured to the housing by means of a support mounting with a counter blade attached to the mounting at the point spaced inwardly from the inner surface of the housing. The counter blade extends in the axial direction in generally the same manner as the stirrer blades. The stirrer blades. during rotation. pass between the counter blades and the inner surface of the housing and afford a scraping or cleaning effect on the housing wall and. in combination with the counter blades. a kneading effect on the material within the housing. Similarly. the counter blades provide a cleaning or scraping effect on the surface of the agitator and also on the axially facing surfaces of the plate-like elements.  
  Nowadays frequent use is made of paddle dryers for chemical reactions and thermal processes. Such dryers consist of a horizontally arranged cylindrical housing provided with a revolving agitator on which agitator arms having blade-like extremities are fixed. The use of such machines is limited basically because of the inadequacy of the mixing and kneading action. that is. the interchange of the material when it is in the pasty state. Moreover. only about half of the heated surfaces in such dryers are continuously cleaned and. as a result. the heat transfer within the dryer is impaired.  
  As compared to the prior art. in the present invention. it is possible to increase the heat transfer surface and to raise the coefficient of heat transmission through such surfaces by affording a continuous cleaning action of the surfaces. Furthermore. it is also possible to provide a satisfactory kneading effect even when the materials being processed are in the pasty state.  
  The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention. its operating advantages and specific objects attained by its use. reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.  
 BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:  
  FIG. I is a longitudinal sectional view through a mixing and kneading device. taken along the line III of FIG. 2;  
  FIG. 2 is a cross-sectional view of the mixing and kneading device;  
  FIG. 3 is a half cross-sectional view of another embodiment of the kneading device shown in FIGS. 1 and 2;  
  FIG. 4 is a half cross-sectional view of still another embodiment of the mixing and kneading device;  
  FIG. 5 is a developed view of an agitator element used in the present invention;  
  FIG. 6 is another developed view of a different agitator element for the present invention; and  
  FIG. 7 is a developed view of a third agitator element for use in the present invention.  
 DETAILED DESCRIPTION OF THE INVENTION The basic concept of the present invention is illustrated in FIGS. 1 and 2. The mixing and kneading device includes a generally horizontally arranged housing 1 with an agitator shaft 20 rotatably mounted within the housing. At its opposite ends, the housing is closed by walls l0, 15. The agitator shaft 20 is spaced radially inwardly from the inner surface of the housing I and a plurality of plate-like agitator elements 25 are fixed to the agitator shaft and extend outwardly toward the housing in planes extending substantially normally of the axis of the agitator shaft. As can be noted in FIG. I, a number of the planes of plate-like elements 25 are spaced axially apart along the length of the agitator shaft. Further. in FIG. 2 it can be observed that in each plane, the plate-like elements 25 are spaced circumferentially apart.  
  The housing I is provided with a heating jacket or heating duct 2. For introducing the material to be processed into the housing and for venting vapors. one or a number of connecting pieces 3 are provided on the top of the housing. When the mixing and kneading of the material is completed. the product is withdrawn through lower connecting piece 4. Members 5 support the housing in stationary positions.  
  End wall 10 of the housing is provided with a stuffing box 13 and a cage 11 extends outwardly from the end wall and supports a bearing 12 for the agitator shaft end 21. At the opposite end of the housing. end wall 15 has a stuffing box 18 and a cage 16 extends outwardly from the end wall and supports a bearing 17 for the opposite agitator shaft end 22. The ends 21 and 22 of the shaft provide support so that it can be rotated within the housing by a driving motor. not shown. via a V-belt pulley 23 and a slip-on transmission 24.  
  As shown in FIGS. 1 and 2, an agitator arm or stirrer blade 26 is secured to the radially outer edge of each of the plate-like elements 25. In FIG. 2 the radially outer surface of the stirrer blade 26 is coincident with the radially outer edge of the plate-like element and both are spaced very closely from the inner surface of the housing 1. Further, the plate-like element 25 is relatively narrow in the axial direction of the shaft 20 while the stirrer blades 26 extend axially from both sides of the blade-like elements.  
  The agitator shaft 20 and the elements 25 can. as a rule. be heated or cooled with the input of the heating or cooling medium through connecting piece 29 and with the return of the medium taking place through the connecting piece 30.  
  Because of their position relative to the inner surface of the housing 1, the stirrer blades 26 can effect a scraping or cleaning action along the inner surface. While the plate-like elements 25 located intermediate the ends of the housing have the stirrer blades 26 extending from each of their axially facing sides. the plate-like members located adjacent the end walls of the housing have agitator arms or stirrer blades 27, 28 which project only inwardly from the plate-like elements toward the opposite end of the housing. The plate-like elements associated with the agitator arms or stirrer blades 27, 28 provide a cleaning or scraping action on the end wall of the housing while the stirrer blades 27, 28 clean the surface of the housing adjacent the end walls.  
  From FIG. 1 it can be noticed that the adjacent ends of stirrer blades 26 extending from the plate-like elements 25 in planes on the agitator are spaced apart to provide a slot 31. In the area or axial extent of the slot 31 the stirrer arms 26 do not pass over the inner surface of the housing. In the open space provided by the slots 31 sturdy mounting supports 32 are secured to the inner surface of the housing and extend radially inwardly for a distance at least slightly greater than the dimension between the inner surface of the housing and the radially inwardly facing surface of the stirrer blades 26. The mounting supports 32 form part of stationary counter elements and the radially inner part of the counter elements consists of a counter blade, as shown in FIG. 2, made up of an axially arranged kneader arm 35, a pair of arms 36 extending radially inwardly from the opposite ends of the kneader arm,  
 and an axially extending scraper 37 extending between the radially inner ends of the arms 36. The edges of the arms 36 are closely spaced from the adjacent surfaces of the plate-like elements 25 and the scraper 37 is similarly closely spaced from the surface of the agitator shaft so that they provide a cleaning or scraping action as the plate-like elements and stirrer blades rotate past them. In a preferred embodiment, the counterelements as shown in FIGS. 1, 2, 3 and 4, are mounted on covers or panels 6 which can be removed from the housing to gain access to the interior of the device so that it can be cleaned.  
  To provide a more complete picture of the counter blades, a portion of FIG. 1 is shown cut away revealing the counter blades as having a frame-like construction. In other words. the kneader arm 35 and scraper 37 form axially extending members of the frame while the arms 36 define its radial members with these parts defining the openings through the counter blades.  
  When the agitator shaft 20 is rotated, the material within the housing is rotated by frictional contact with the plate-like elements or by the blade effect of the agitator arms or the stirrer blades 26. During this procedure, the agitating and mixing of the material is substantially increased by the counter-elements. This is especially true in the case of pasty materials, where the mass of material is forced by the stirrer blades 26 through the space between the inner wall of the housing 1 and the kneader arm on the counter-element and is subjected to an intense shearing and kneading effect. The arms 36 and the scrapers 37 which form the blade or counter-blade portion of the counter-elements also serve. as mentioned above. to provide a continuous cleaning action of the heatable or coolable surfaces of the agitator shaft 20 and of the axially facing surfaces of the plate-like elements mounted on the shaft. Furthermore. the counter-elements are also designed to contribute substantially to the kneading effect. In FIG. 3 the arms 36 have a curved or bent arrangement extending oppositely to the direction in which the agitator shaft 20 rotates. This arrangement of the counterblades serves to direct the material from the agitator shaft upwardly into the space between the housing and the kneader arm 35.  
  In FIGS. 1 and 2 a single axially extending row of counter-elements is shown, however, it is also possible to arrange two or more rows of such counter-elements. In such a case, the counter-blades which, viewed in the direction of rotation of the agitator, are mounted in series on the housing, can be of different designs. For instance, one of the counter-blades can, viewed from the holding support, be arranged so that it only extends in the axial direction from one side of the mounting support 32. Similarly, the next counterblade can be arranged so that it extends from its mounting support in the opposite direction. That is, as viewed in the drawings, one counter-blade would extend to the left and the next counter-blade would extend to the right. With regard to the shape of the counter-blade there are many possible variations. As illustrated in the drawings. the counter-blade can be provided with a frame-like configuration or with a large areal surface. Frequently, as a result of the appropriate shape of the kneader arm 35 in combination with the shape of the stirrer blade 26, the kneading effect can be improved, for instance, through the formation of a conically-shaped space between the two kneading parts.  
  There are many possible variations in the arrangement of the plate-like elements on the agitator and the stirrer blades positioned on the elements. In addition to the selected number of plate-like elements used. and their dimension and shape, one particular arrangement, as illustrated in FIG. 4, is important. As compared to the plate-like element 25 in FIGS. 2 and 3, in FIG. 4 the radially outer edge of the plate-like elements 39 are not as close to the inner surface of the housing so that the stirrer blade 36 projects outwardly from the radially outer edge of the element 39, that is, the radially outer edge of the element 39 is spaced from the inner surface of the housing by the radial dimension of the stirrer blade 26 and the clearance between the stirrer blade and the housing. In this arrangement the radially extending arms 36 of the counter-blade provides the cleaning action for the entire radial extent of the element 39 as differentiated from the arrangement shown in FIGS. 2 and 3.  
  FIGS. 5, 6 and 7 illustrate some of the many possible arrangements of the agitator elements and the counterelements. In these figures the cylindrical housing 1 is developed or rolled out into a flatplane. Accordingly, the agitator or plate-like elements 25 have their contour projected onto the plane of the housing. In FIG. 5 one-half of the device is illustrated with all of the disk elements being arranged perpendicularly to the axis of the agitator shaft 20 and with the stirrer arms 26 arranged not axially but at an angle to the axial direction of the shaft. If the elements 25 move in the direction of the arrow. this angular position of the stirrer blades represented by reference numeral 40 causes a movement of the material being processed toward the center of the device. In this arrangement the counter-blades 41 of the counter-elements are arranged in the axial direction of the shaft. Further. the elements and their stirrer blades 27, 28 located at the opposite ends of the housing provide a scraping or cleaning action with their edges 42. 43 of the end walls 10, 15 and inaddition, their half stirrer blades are arranged to direct the material toward the center of the device.  
  A more preferred embodiment of the arrangement of the plate-like elements and the counter-elements is shown in FIG. 6 where the stirrer blades are not arranged exactly along the axial direction of the shaft but are arranged along a line corresponding to the transportation angle of the stirrer blades. In other words. as compared to FIG. 5, the stirrer blades are in alignment rather than being in a staggered arrangement. This arrangement provides the advantage that the conveyance of the material being processed from one stirrer blade is not obstructed by the projecting edge of the next blade. In this arrangement the counter-blades 44 or at least their kneader arms are also positioned at an angle to the axial direction of the shaft and housing with the angle being arranged counter to that of the angle 40 of the stirrer blades. This scissor-like arrangement is capable of increasing the kneading effect within the device.  
  There is the drawback in the arrangements of FIGS 5 and 6 in that the passage of the stirrer blades through the kneading slots between the housing and the kneader blades of the counter-blades always occurs at the same time. As a result there are intense surges of power required by the device each time stirrer blades pass through the kneading slot. that is, three times during each complete cycle of rotation of the agitator shaft. To overcome this disadvantage, FIG. 7 shows a staggered arrangement affording a better power distribution. In FIG. 7, the stirrer blades 51 are arranged on the plate-like elements so that only one of the blades 51 passes through the kneading slot at a given movement during rotation of the agitator shaft. The same purpose is likewise served by the displacement of the plate-like elements on the righthand side of the center line with respect to the plate-like elements on the left by a certain peripheral angle.  
  All of the figures and embodiments described illustrate a device for operation in a batch-type process, in which, under normal conditions, the material is conveyed from the end walls toward the center as it is rotated and then moves back again toward the end walls. The principle underlying this mode of operation can. however, be implemented as a continuously operating machine if all agitator arms or stirrer blades, or at least the major portion of them, have their angles set in such a way that the material is conveyed from its input at one end of the device to its output at the other end.  
  The particular advantage of the machine, that is, that the major portion of the surfaces contacted by the material is cleaned continuously, is of significance regarding the heating and cooling of the processed materials, since. on one hand, the heat transfer coefficient is improved and. on the other, build up of material on the heating or cooling surfaces is avoided. The heating and cooling of the surfaces can be performed in a known manner.  
  Occasionally, buildup or incrustation may develop which is extraordinarily stubborn and, even though there is a very narrow clearance between the surfaces to be cleaned and the members doing the cleaning, it is extremely difficult to remove. However, it has been found that such incrustations can be removed if the agitator or housing. that is one of the cooperating members. is allowed to vibrate with an amplitude of about half the clearance between the member being cleaned and the one doing the cleaning, in view of the fact that the vibration impacts effectively remove the incrustation.  
  While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.  
 What is claimed is:  
  l. A mixing and kneading device for the mechanical, chemical and thermal treatment of liquid, pasty and pulverant products with or without the input or output of gases and vapor, comprising a cylindrical housing, an inlet in said housing for introducing materials to be processed into said housing, an outlet in said housing spaced from said inlet for withdrawing the materials from said housing, an agitator positioned within and having its axis extending in the axial direction of said housing, said agitator mounted for rotation about its axis, a plurality of plate-like elements secured to and extending radially outwardly from said agitator for rotation therewith, said plate-like elements disposed in a number of planes extending transversely of the axis of said agitator, a stirrer blade extending in the axial direction of said agitator and fixed to each said plate-like element on the radially outer periphery thereof. the radially outer periphery of said plate-like elements being spaced closely inwardly from the inner surface of said cylindrical housing so that as said agitator rotates at least said stirrer blade passes in closely spaced relation to the inner surface of said cylinder housing and effects a cleaning thereof. a plurality of stationary counterelements secured to the inner surface of said cylindrical housing and extending radially inwardly towards said agitator, each said counter-element comprising a mounting support secured to the inner surface of said cylindrical housing and extending radially toward said agitator for a dimension at least slightly greater than the dimension between the inner surface of said cylindrical housing and the radially-inwardly facing surface of said axially extending stirrer blades, said mounting support being positioned in the axial direction of said cylindrical housing so that it is positioned between the adjacent ends of said stirrer blades located in adjacent planes of said blades, a counter-blade secured to the radially inner end of said support mounting and extending inwardly therefrom toward said agitator so that the radially inner edge of said counter-blades is spaced closely from and acts as a scraper for said agitator, said counter-blades extending in the axial direction of said plate-like element with its radially outer edge being approximately coincident with the radially outer edge of said plate-like element.  
  3. A mixing and kneading device, as set forth in claim 1, wherein each said stirrer blade is fixed to and extends radially outwardly from the radially outer edge of said plate-like element so that there is a radially extending open space between the radially outer side of said plate-like element and stirrer blade.  
  4. A mixing and kneading device, as set forth in claim 1, wherein said stirrer blades extend in parallel relation with the axial direction of said cylindrical housing.  
  5. A mixing and kneading device, as set forth in claim 1, wherein said stirrer blades are arranged angularly to the axial direction of said cylindrical housing.  
  6. A mixing and kneading device. as set forth in claim 1, wherein a number of radially extending planes of said plate-like elements are arranged along said agitator with a plurality of said plate-like elements in each of the radially extending planes and one said counter element located between each pair of adjacent said radially extending planes.  
  7. A mixing and kneading device, as set forth in claim 6, wherein at least two circumferentially spaced counter-elements are located between each pair of adjacent said radially extending planes of said plate-like elements.  
  8. A mixing and kneading device, as set forth in claim 7, wherein each said counter-element has its said counter blade extending in the axial direction from only one side of said mounting support and on adjacent said counter-elements between the same pair of radially extending planes of said plate-like elements said counter-blades extend in opposite directions.  
  9. A mixing and kneading device, as set forth in claim 6, wherein said counter-blade extends laterally from said support mounting in the axial direction of said cylindrical housing for a dimension so that it is closely spaced from at least one said plate-like element in the adjacent planes of said plate-like elements for affording a scraping or cleaning action on the surface of said plate-like element.  
  10. A mixing and kneading device. as set forth in claim 9. wherein said counter-blades extend in parallel relation with the axial direction of said cylindrical housing.  
  11. A mixing and kneading device, as set forth in claim 9, wherein said counter-blades have a curved configuration viewed in the plane of said plate-like elements.  
  12. A mixing and kneading device, as set forth in claim 9. wherein said counter-blades have a frame-like shape forming a kneading opening therethrough.  
  13. A mixing and kneading device. as set forth in claim 12, wherein the frame-like shape of said counterblades is formed by an axially extending kneader arm secured to and extending in the axial direction from both sides of said mounting support. a pair of axially spaced arms each extending radially outwardly from an opposite end of said kneader arm toward said agitator and a scraper extending between the radially inner ends of said arms and having its radially inner surface spaced closely from the surface of said agitator, the radially outer side of said scraper being spaced radially from the radially inner side of said kneader so that said kneader arm. said arms and said scraper define the kneading opening through said counter-blades.  
  14. A mixing and kneading device. as set forth in claim 1, wherein said counter-blades extend at an angle to the axial direction of said cylindrical housing.  
  15. A mixing and kneading device. as set forth in claim 1, wherein said cylindrical housing having displaceable panels and said counter-elements attached to said displaceable panels so that said panels can be removed for cleaning the interior of the device.  
  16. A mixing and kneading device, as set forth in claim 1, wherein one of said agitator and said housing is subjected to a vibratory action having an amplitude of one-half to three-quarters of the clearance between the moving parts of said rotatable agitator and the stationary parts of said housing.  
  17. A mixing and kneading device, as set forth in claim 1, wherein said plate-like elements are arranged in a number of axially spaced radially extending planes having said plate-like elements spaced apart in the circumferential direction of said agitator within each of said radially extending planes so that open spaces are provided between adjacent edges of said plate-like elements.  
  18. A mixing and kneading device, as set forth in claim 1, wherein said cylindrical housing having a closed end wall at each end thereof and at least one said plate-like element located in a plane closely adjacent to each said end wall and having one said stirrer blade fixed to said plate-like element in the plane adjacent the end wall and extending axially therefrom only from the side of said plate-like element facing away from the adjacent said end wall.