Kneader

Abstract: The present invention discloses a kneader having a vessel for housing a material to be kneaded, rotor shafts passing through opposite two lateral walls of the vessel, and blades for kneading the material formed at the outer peripheries of the rotor shafts inside of the vessel. In the kneader, those portions of the rotor shafts located inside of the vessel, are straight, and an ex­ ternal member having the blades is fitted on each of the rotor shafts at the straight portion thereof. The exter­ nal members have both ends which extend to the outside of the opposite two lateral walls of the vessel, and are secured to the rotor shafts outside of the opposite two lateral walls of the vessel.

Description: Background of the Invention The present invention relates to a kneader for kneading a viscous material such as plastic, rubber, etc., and more particularly to the arrangement of the rotor shafts thereof. There is known a method for making the rotor shafts of a kneader, by which after the shafts have been lathed, blades separately made are welded to the shafts. According to this method, the welding heat generates thermal stress on the shafts. This may cause the shafts not to be axially aligned. In a pressure-type kneader for kneading a material under a high pressure in an enclosed space, the material leaks from the kneading chamber to the outside or the material leaks in the kneading chamber to the spaces inside of the blades after passing through gaps, if any, between the shafts and the blades. Therefore, the kneader needs to be sealed against such material leakage. Further, when the shafts are made separately from the blades, a corrosion resisting material such as ceramic, stainless steel, engineering plastic may be used as the blade material. When the blades made of such corrosion resisting material are to be secured to the shafts, it should not be allowed to use, in the kneading chamber, bolts, screws or other members which may be corroded. Further, in the kneader a heat transfer medium is generally circulated inside of the blades to cool or heat a material to be kneaded. It is therefore preferable to provide wide spaces in the blade insides to enhance the heat conduction with respect to the blade surfaces. US-A-2 495 242 discloses a mixing apparatus comprising a mixing chamber and rotor shafts to which stirrers are affixed passing therethrough. Summary of the Invention It is an object of the present invention to provide a kneader having rotor shafts which solve and satisfy all the problems and requirements above-mentioned. According to the invention there is provided a kneader comprising a vessel for holding a material to be kneaded; a rotor shaft passing through the vessel; bearings supporting the rotor shaft externally of the vessel; a blade assembly affixed to the rotor shaft, characterised in that the blade assembly comprises a cylindrical sleeve fitting over the rotor shaft and a blade extending outwardly from the sleeve, the cylindrical sleeve of the blade assembly extending outside the vessel, and in that the blade assembly is secured to the rotor shaft by means other than welding. The separate arrangement of the rotor shafts from the blades reduces the number of machining steps for the rotor shafts, and eliminates thermal stress which would otherwise be generated by welding or the like. This improves the precision in straightness of the rotor shafts. Further, the external members extend to the outside of the lateral walls of the vessel. This enables the external members to be secured to the rotor shafts outside of the vessel. This increases the contact areas of the external members with the rotor shafts, thereby to improve the adhesion of the external members to the rotor shafts. When the external members are made thin, the conduction of heat from the heat transfer medium to the material is improved. Brief Description of the Drawings Figure 1 is a vertical section view of an embodiment of the present invention; Figure 2 is a section view taken along the line Y-Y in Figure 1; and Figure 3 is an enlarged view of a portion in Fig. 1. Description of the Preferred Embodiments The following description will discuss in more detail the present invention with reference to the attached drawings which show an embodiment of the presnt invention, by way of example. Figure 1 is a vertical section view of an embodiment of the present invention. Two rotor shafts 5 pass through opposite two lateral walls 2A, 2B of a vessel 1 for housing a raw material to be kneaded. Each of the rotor shafts 5 is supported by bearings 4A, 4B and driven in rotation by a motor (not shown) through a transmission mechanism such as gears, speed reduction means, etc. Sealing means 3A, 3B for preventing the raw material from leaking are disposed at those portions of the lateral walls 2A, 2B through which each rotor shaft 5 passes. A pressurizing lid 6 is disposed above the vessel 1, the lid 6 being vertically movable for pressurizing the raw material by a hydraulic cylinder. At least that portion of each rotor shaft 5 which is located inside the vessel 1, has a constant diameter and does not have an intermediate projection. An external member 7 is fitted on each rotor shaft 5 at the outer periphery thereof. The external members 7 include: cylindrical portions which extend to the outside of the lateral walls of the vessel and which are fitted on the rotor shafts 5; blade portions 10 which form spaces 9 together with the rotor shafts 5; and flange portions 11 which constitute part of the sealing means; the cylindrical portions, the blade portions 10 and the flanges 11 being integrally formed. The cylindrical portions of the external members 7 at both ends thereof are shrink-fitted to the rotor shafts 5. As shown in Fig. 3, the flange portions 11 are disposed for forming sealing surfaces together with the end surfaces of cylindrical packings 12. Rings 17 made of a hard metal material such as ceramic, etc. may be embedded in the sealing surfaces of the flange portions 11. The rotor shafts 5 are provided in the insides thereof with passages for heat transfer medium 13, 14 which extend from the space portions 9 in the external members 7 to one ends of the rotor shafts 5. The passages 13, 14 cause a heat transfer liquid for cooling or heating to be circulated. More specifically, the circulation passages formed in the external members 7 start from the tips of the passages 13, enter into points A, pass through points B, reach to points C along the outer peripheries of the rotor shafts 5, pass through points D and return to the passages 14. The heat transfer liquid is moved from one space portions 9 to the other space portions 9 while passing through passages along the outer peripheries of the rotor shafts 5 as shown in Fig. 2. The heat transfer liquid may also be circulated in the reverse direction from the points D to the points A. The external members 7 are provided in both ends thereof with loop-like grooves in the circumferential direction thereof. Resin is introduced under pressure to these grooves through inlet ports 16A, 16B, thereby to form packings 15A, 15B. It is noted that the packings 15A, 15B may be omitted if the shrink-fit of the external members 7 at both ends thereof securely prevents the heat transfer liquid from leaking. According to the present invention, the external members 7 are preferably made by the lost-wax process. The material for making the external members 7 includes stainless steel, ceramic, heat-resisting plastic, a variety of metals, and other composite material. According to the kneader of the present invention, external members are fitted on the rotor shafts at the outer peripheries thereof, and have end portions which extend to the outside of the lateral walls of the vessel. The external members are secured to the rotor shafts outside of the vessel lateral walls. This eliminates the possibility that a material to be kneaded leaks through gaps between the rotor shafts and the external members. Such arrangement also simplifies the structure of the vessel interior and improves the reliability. According to the present invention, even though the external members are made thin, the contact areas between the external members and the rotor shafts are increased to improve the adhesion of the external members to the rotor shafts. This also improves the heat efficiency.

Claims: A kneader comprising a vessel (1) for holding a material to be kneaded; a rotor shaft (5) passing through the vessel; bearings (4A, 4B) supporting the rotor shaft externally of the vessel; a blade assemly (7) affixed to the rotor shaft, the blade assembly comprising a cylindrical sleeve fitting over the rotor shaft and a blade (10) extending outwardly from the sleeve, characterised in that the cylindrical sleeve of the blade assembly extends outside the vessel, and in that the blade assembly (7) is secured to the rotor shaft (5) by means other than welding. A kneader according to claim 1 in which the blade (10) is formed by an eccentrically widened portion of the cylindrical sleeve of the blade assembly (7), defining a space (9) between the blade and the rotor shaft (5) through which a heat transfer medium for cooling or heating can circulate. A kneader according to claim 1 or 2 in which the cylindrical sleeve of the blade assembly (7) is fitted to the rotor shaft (5) by shrink fitting. A kneader according to any preceding claim, in which the cylindrical sleeve of the blade assembly (7) is fitted to the rotor shaft (5) by means of plastic packing (15A, 15B) introduced under pressure into circumferential grooves formed in the sleeve and/or in the rotor shaft in the vicinity of the ends of the blade assembly.

Inventors: MORIYAMA MASAO, MORIYAMA, MASAO
Applicants: MORIYAMA MASAO, MORIYAMA, MASAO
Application year: 1988
Main classification: B01F15
IPC codes: B29B7, B01F15, B01F7