GB2025778A

GB2025778A - Mixing machine

Info

Publication number: GB2025778A
Application number: GB7923116A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-07-19
Filing date: 1979-07-03
Publication date: 1980-01-30
Also published as: GB2025778B; FR2431320A1; BE877554A; IT7924495A0; NL7905107A; IT1122637B; DE2831686A1

Abstract

A mixing machine, more particularly for building materials, is designed for homogeneous mixing and dust proofing of its wearing surfaces. The machine comprises a cylindrical container (1) and a top cover 4 unit therefor housing a driven, rotary carrier 11 which journals two sets of rotary tools (21, 22) which are driven from the carrier in opposite directions, at the same speed, via a toothed rim (18) of the carrier. The tools of each set are disposed respectively in perpendicular planes and likewise, corresponding tools (21 and 22) respectively of the sets, the pairs of tools (21 and 22) being disposed with their axes of rotation parallel, diametrically with respect to the cylindrical axis (5) of the container. Further the axes of rotation of the tools of each set are positioned close together so that the tools sweep intersecting circular paths of a diameter equal to the container radius. In this way no dead spaces are left in the container and homogeneous mixing is achieved. Also, the top cover unit houses all the bearings which are thereby protected from dust. <IMAGE>

Description

SPECIFICATION Mixing Machine The invention relates to a mixing machine.

It is known to provide a mixing machine for mixing powdery, granular or small lumpy substances, for example building materials, with or without the addition of liquid.

In one construction, a container is provided which is open at the top and in which there is disposed a central shaft about which a frameshaped rotary carrier is driven in rotation.

Mounted in the frame are the drive shafts of a pair of mixing tools, drive pinions of which mesh with a common central gearwheel which is set in rotation by a drive motor through a mitre gear and an intermediate shaft. Such a construction provides only indifferent mixing and a homogeneous mixture is not produced. It is true that the two mixing tools execute a rotary movement about the central axis of the container apart from their own rotary motion, but they only cover a portion of the mixing space in the container so that additional guide vanes have to be provided to avoid dead spaces and to move and restore material outside the compass of the mixing tools back into the working region of the mixing tools.

It is an object of the invention to provide an improved mixing machine for the purpose stated.

In accordance with the invention a mixing machine comprises a substantially cylindrical, stationary mixing chamber, mixing tools which are driven in rotation about axes of rotation parallel to the cylindrical axis of the container and additionally execute a rotary movement about said cylindrical axis, the mixing tools being arranged in pairs having drive shafts which are mounted diametrically with respect to one another in relation to said cylindrical axis in a rotary carrier and each of which is provided with a drive pinion, there being drive means drivable to rotate the rotary carrier, and in which the mixing tools, the rotary carrier, the drive means and said pinions are incorporated as parts of a cover unit for the container which can be placed on and removed from the container, said unit comprising a stationary, internally toothed rim concentric with the cylindrical axis of the container and meshing with the drive pinions, of a first pair of said mixing tools, a pivot bearing for the rotary carrier, and a second pair of said mixing tools, the first and second pairs of tools forming two sets of tools, of which the mixing tools rotate in opposite directions along intersecting circular paths.

A mixing machine according to the invention provides a mixing compartment which is shut off from the environment but is easily accessible at any time by removing the cover unit. The mixing compartment may be swept completely by the mixing tools so that no dead spaces are left in which unmixed material can accumulate. By combining all the movable parts as a component of a structural cover unit, a shielding of all wearsensitive parts can be achieved by simple means, so that the mixing machine can run for a long life with very little servicing.

A specific embodiment of the present invention will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which: Fig. 1 is a simplified section on the line I--I in Fig. 2 of a mixing machine of the invention; and Fig. 2 is a diagrammatic illustration of the machine in section on the line Il-Il in Fig. 1.

Referring now to the accompanying drawings, the mixing machine comprises a stationary cylindrical container 1 with a material inlet opening 2, which may be replaced by a plurality of material inlet openings for the separate feeding of the substances to be mixed, if this is desired. A central bottom opening 3 in the plane bottom of the mixing container can be closed or freed for emptying purposes by a flap or a slide 3'. A structural cover unit 4 mounted on the mixing container 1 closes the inerior of the container at the top and is removable upwardly to expose the interior of the container. The unit 4 includes all the moving parts of the mixer with the exception of the mixing tools themselves and excludes dust and the like wear-producing particles.Supported diametrically in relation to the central axis 5 of the container on the top of the unit 4 are two drive motors 6 and 7, the shafts 8 of which each drive a pinion 9, 10. The pinions 9, 10 mesh with the externally toothed rim 11' of a rotary carrier 11, which is mounted for rotation about the central axis 5 of the container by means of a bearing arrangement 12 in a peripheral part 1 3 of the unit 4. The rotary carrier 11 in turn journals, by means of bearings, 14 parallel drive shafts 1 5 which are aligned diametrically with respect to one another in relation to the axis 5 and which each carry a drive pinion 16, 16' at their upper end.Furthermore, the rotary carrier 11 likewise journals, by means of bearings 14, parallel drive shafts 15' which in turn are aligned diametrically with respect to one another in relation to the axis 5 and the upper ends of which are each connected to a drive pinion 17 or 17'.

The drive pinions 16, 16' mesh directly with an internal toothed rim 18, concentric with the central axis 5 of the container, at the peripheral portion 13 of the unit 4 and roll on the rim 18 as soon as the rotary carrier 11 is set in rotation.

Accordingly, the drive pinions 16, 16' are driven in rotation. The drive pinions 17, 17' mesh with the drive pinions 1 6 and 16' respectively with the result that, with like drive pinions as provided, the drive pinions 17, 17' are driven in rotation at the same speed as the pinions 16, 16' but in the opposite direction of rotation. An odd gear ratio is preferably selected between the speed of the drive pinions 16, 16', 17, 17' and the speed of the rotary carrier 11, to improve the covering area of the movement of the mixing tools.

Each mixing tool is symmetrical with respect to its axis of rotation and comprises an upper, inverted V-shaped portion 1 9 extending downwards from a hub region and two mixing fingers 20 extending downwards from the ends of the Vee arms. The mixing tools 21 secured to the lower ends of the two drive shafts 1 5 form a first pair of tools spaced diametrically oppositely on opposite sides of the central axis 5 of the container. The mixing tools 22 secured to the lower ends of the drive shafts 15' form a second pair of tools spaced diametrically oppositely on opposite sides of the axis 5 of the container. Each mixing tool 21 and its adjacent mixing tool 22 to the same side of the axis 5 form a co-operating set of tools.

The mixing tools 21, 22 belonging to each cooperating set of tools have an angular phase displacement of 900 in relation to one another in such a manner that when the one tool is aligned parallel to the coordinate plane 24 (Fig. 2), the other tool is aligned parallel to the coordinate plane 25 extending perpendicular to the plane 24.

Aiso, the sets of tools 21 and 22 have an angular phase displacement of 900 so that when the one mixing tool 21 is aligned parallel to the coordinate plane 24, the other mixing tool 21 is aligned parallel to the coordinate plane 25. The same applies to the mixing tools 22. Apart from this, the mixing tools 21, 22 of each co-operating set are disposed so close together that their fingers 20 sweep intersecting circular paths and the working circles covered by their mixing fingers alternately touch or include the centres of the working circles. In other words, the spacing of the centres of the working circles of the mixing tools of each co-operating set of tools is equal to or smaller than the radius of their working circlets.

As can be seen from Fig. 2, on rotation of the rotary carrier 11, the drive shafts 1 5 travel through a circle of rotary movement with a somewhat larger diameter in comparison to the circle of rotary movement of the drive shafts 1 5'.

The dimensions of the components are so chosen in relation to one another that the mixing fingers 20 of the mixing tools 21 pass close to the side wall of the mixing container 1 and at the same time sweep closely over the bottom of the mixing container.

The cover unit 4 is only illustrated diagrammatically in Fig. 1. It will be understood that sealing means are provided to protect the -bearings and other movable parts, so as to eliminate the admission of particles of material being mixed to the bearings 12 and 14 for example. Also, the central passage in the rotary carrier 11, illustrated in Fig. 1, would preferably have a closure member.

Claims

1. A mixing machine comprising a substantially cylindrical, stationary mixing chamber, mixing tools which are driven in rotation about axes of rotation parallel to the cylindrical axis of the container and additionally execute a rotary movement about said cylindrical axis, the mixing tools being arranged in pairs having drive shafts which are mounted diametrically with repect to one another in relation to said cylindrical axis in a rotary carrier and each of which is provided with a drive pinion, there being drive means drivable to rotate the rotary carrier, and in which the mixing tools, the rotary carrier, the drive means and said pinions are incorporated as parts of a cover unit for the container which can be placed on and removed from the container, said unit comprising a stationary, internally toothed rim concentric with the cylindrical axis of the container and meshing with the drive pinions, of a first pair of said mixing tools, a pivot bearing for the rotary carrier, and a second pair of said mixing tools, the first and second pairs of tools forming two sets of tools, of which the mixing tools rotate in opposite directions along intersecting circular paths.

2. A mixing machine as claimed in claim 1 in which the drive pinions of the mixing tools of the second pair are driven directly by the drive pinions of the mixing tools of the first pair.

3. A mixing machine as claimed in claim 1 or 2 in which the cover unit includes two drive motors which drive the drive pinions arranged diametrically oppositely in relation to the cylindrical axis of the container and drivably engage an externally toothed rim on the rotary carrier.

4. A mixing machine as claimed in any preceding claim in which all the mixing tools rotate at the same speed in an odd gear ratio with respect to the rotary carrier.

5. A mixing machine as claimed in any preceding claim in which each mixing tool is symmetrical in its construction and comprises a V-shaped portion presenting a hub region and two mixing fingers extending from the arms of the V-shaped portion at their ends opposite the hub portion, the mixing tools forming a set of tools having an angular phase displacement of 900 in relation to one another and the mixing tools of the first and second pairs having an angular phase displacement of 900 in relation to one another, the working circles covered by the mixing fingers of the sets of tools each touch or include the centres of the working circles.

6. A mixing machine substantially as hereinbefore described with reference to the accompanying drawings.