US3924835A

US3924835A - Mixer for particulate materials

Info

Publication number: US3924835A
Application number: US410248A
Authority: US
Inventors: Peter Hohnfeld; Hartmut Langenberg
Original assignee: Dierks and Soehne GmbH and Co KG
Current assignee: Dierks and Soehne GmbH and Co KG
Priority date: 1972-10-28
Filing date: 1973-10-26
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09
Also published as: GB1416567A; DE2252996A1; IT995844B

Abstract

A particulate material mixing machine has a horizontal mixing drum which is separable into two parts to gain access to its interior and to internal mixing and material-transfer paddles, the paddles being rotated by two separately supported and driven rotary drive shafts which respectively enter the two parts of the drum and which are aligned when the machine is ready for use, and the paddles being borne by drivingly-interconnected hubs which are designed to slide onto and off the shafts for ease of maintenance.

Description

United States Patent Hohnfeld et al. Dec. 9, 1975 [5 MIXER FOR PARTICULATE MATERIALS 1,017,820 2/1912 Svebilius 416/200 1,385,484 7/1921 Case 220/4 D [75] Inventors- Peter 1,467,537 9/1923 Dornier 416/200 Langenbel'g, Buer, both of Germany 2,010,579 8/1935 Broadfield 259/105 3,526,467 9/1970 Kime 1 416/200 [73] Asslgnee' 23:2 Soehne Osnabrueck 3,652,062 3/1972 Baker 259/68 x Filedi 1973 Primary ExaminerBilly J. Wilhite [21] AppL No; 410,248 Assistant Examiner-Alan Cantor [30] Foreign Application Priority Data [57] CT Oct 28 1972 Germany 2252996 A particulate material mlxing machine has a hor1zontal mixing drum which is separable into two parts to 52 US. Cl. 25 200 gain access its interim and mixing and E Int z material-transfer paddles, the paddles bemg rotated by [58] Field of 64 105 two separately supported and driven rotary drive S 220/4C f 8 6 shafts which respectively enter the two parts of the drum and which are aligned when the machine is [56] References Cited ready for use, and the paddles being borne by drivingly-interconnected hubs which are designed to UNITED STATES PATENTS slide onto and off the shafts for ease of maintenance. 444,470 1/1891 Villavaso 1. 259/21 917,206 4/1909 Watts 416/200 8 Clams, 5 Drawmg Flgllres U.S. Patent Dec. 9, 1975 Sheet1of4 3,924,835

US. Patent Dec. 9, 1975 shw 2 of4 3,924,835

US. Patent Dec. 9, 1975 Sheet4 0f4 3,924,835

MIXER FOR PARTICULATE MATERIALS The present invention relates to a mixing machine for the continuous mixing and preparation of particulate materials such as powders and granular or small-sized aggregate products.

In the past, frequent attempts have been made to develop continuously-operating mixers, particularly for mixing synthetic materials. In addition to horizontal mixers of a type having horizontal mixing vessels containing mixing paddles which rotate about horizontal axes, vertical mixers have been proposed. Vertical mixers have vertically disposed mixing vessels and vertical paddle-carrying shafts rotating therein. Such mixers utilise the gravitational force to assist in moving the material being mixed through the mixers. It has been proposed, furthermore, to arrange conventional high speed mixers one after the other in cascade fashion and to connect them together through intermediate connecting ducts in such a fashion that the material being mixed is compelled to move successively from mixer to I'I'IIXBI'.

Previous attempts have failed to provide a satisfactory mixer which adequately meets the requirements of practice, in particular, in the field of the preparation of synthetic materials. Only with extruders has it been possible to operate continuously, to plasticise synthetic material, granulate and feed the resulting essentially homogeneous plasticised synthetic material mass continuously to an extrusion head. An extruder which has a mixing tool in the form of a worm or screw-feed auger inside a mixing vessel, subjects the synthetic material being processed to a relatively high pressure and is designed to produce an effect quite different from the effect of mixing and preparation of synthetic materials required of high speed mixers. High speed mixers are designed to produce material which is fluid in the prepared form, generally granulate and not a homoge neously plasticised mass. In this context, preparation takes place in a state substantially of no pressure, and the particles to be mixed and prepared are subjected to vigorous eddying motion which, whilst maintaining the fluidity, achieves the desired mixing effect quickly and in a controllable manner.

The adaptation of the principles of known batchoperating high speed mixing to continuous mixing could not be achieved satisfactorily amongst other things because known mixing machines could not be adequately controlled to produce the requisite uniformity of mixture. Furthermore, known machines could not be adapted economically to the very widely varying conditions which are encountered in the practice.

To this end the machine in accordance with the invention, commencing from the type introductorily described, is primarily characterised in that the tool carrier shaft consists of two axially aligned, independent shaft sections, those of whose ends which are disposed away from one another and outside the mixing chamber are equipped with single-ended bearings, can be separately driven and are fitted with tool sets arranged on them in an exchangeable fashion. In order to be able to adjust the material flow conditions in a zonally differentiated fashion in the mixer chamber and in order to control the swell time there, preferentially each shaft section will be capable of speed variation and/or versible.

The mixer vessel can furthermore advantageously consist of at least two vessel section with radial separating places, a main separating plane being disposed between adjoining vessel sections, in fact between the internal ends of the shaft sections. A further embodiment of the invention is characterised in that one of the two machine sections located in one side of the main separating plane or joint plane, is supported in such a fashion as to be capable of opposite axial displacement relatively to the other, or, instead of this or in addition thereto, is supported in such a fashion as to be capable of pivoting about a tilting axis disposed parallel to and an interval from the common axis of the shaft sections. This kind of design makes it possible to achieve a rapid access to the shaft sections and to the tool sets arranged thereon, so that quick and easy cleaning, repair and resetting operations can be carried out.

The tool sets will preferentially comprise a substan tially ring-shaped hub which can be slid on to the associated shaft section, which hub is provided on its end face with drive pins and bores, so that in each case adjacent shaft section mounted hubs can be coupled to one another, the hubs of the tool sets arranged in each case on a shaft section, in each case forming a casing or envelope surrounding the shaft. In this context, the particular hub located nearest to the external end of a shaft section, can be in driving engagement with the shaft through the agency of a spring ring element, and thus form the initial element from which the rotational drive is consecutively transmitted to the hubs of the tool sets. In order to ensure that the tool set hubs in each case arranged adjacent one another upon a shaft section, are firmly held together, it is provided, in accordance with the invention that the hub in each case assigned to the internal end of a shaft section, embraces an end cap fitted over the shaft end, and is attached to the shaft end through a set of axial screws distributed around the shaft axis. The axial screws, which perform their securing function even if the directions of rotation are opposite, constitute fixing elements by which all the hubs arranged upon a shaft section are held together and maintained in a mutual driving relationship. The shaft section here, as far as all the intervening tool set hubs are concerned simply performs a supporting function so that the tool set, on the lease of the cap-like hub of the particular innermost tool set, can all be rapidly withdrawn from the shaft and re-assembled on it again in any arbitrary order or arrangement, and this also includes the possibility of mutual angular stagger in the circumferential sense.

At least some of the tool sets will have paddles or blades with a certain angle of incidence, not unlike a propeller, this in a manner known per se. The position of the tool paddles or blades within a tool set, will conveniently be the same throughout. In association with hub rings simply acting as spacers and tool sets whose blades do not exhibit any angle of incidence, it is possible within the machine to build up tool set groups which are optimally matched to the particular special conditions governing synthetic materials which require mixing, in the mixer chamber of the vessel flow conditions being developed, in a state of continuous material transfer, which satisfy all requirements of the particular case.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a simplified side elevation of a mixing machine embodying the invention;

FIG. 2 is a plan view of the machine shown in FIG. 1;

FIG. 3 is an end elevation of the machine shown in FIGS. 1 and 2;

FIG. 4 is an end elevation similar to FIG. 3, of part of the machine along the line IVIV in FIG. 2, and

FIG. 5 is a longitudinal section through the mixer vessel on the line VV of FIG. 2.

The machine illustrated in the drawing has a cylindrical mixer vessel 1 having a top inlet connection 2 at one end and a bottom discharge connection 3 at its other end. The vessel 1 has its central axis 4 horizontal. In this instance, the mixer vessel 1 is composed of four vessel sections, 5, 6, 7 and 8. The two central sections 6, 7 are joined together about a central plane which is substantially normal to the axis 4, i.e. the plane is radially disposed. The

vessel end sections

5 and 8, which adjoin the sections 6, 7 about radial planes, 10, 11, constitute input and discharge zones of the mixer chamber respectively. The two

end sections

5, 8 are attached to bearing

units

12 and 13, by flange connections. Conveniently the mixer vessel 1 has a double-wall construction, so that heating media or coolants can flow in a space between the two walls. It is advantageous for each

section

5, 6, 7 and 8 to be a double-wall unit which is equipped with its own separate heating agent or coolant connections (not shown). The vessel sections can then be supplied with heating media or coolant individually to enable differential control of the temperature of the internal walls of the vessel 1 along its length.

The machine incorporates a tool carrier consisting of two colinear shaft sections 14, whose common axis coincides with the axis 4. The two

shaft sections

14, 15 are mounted in single-ended fashion in the

bearing units

12, 13 at their opposite ends which are located outside the mixer chamber. The inner portions of the

shaft sections

14, 15 are consequently cantilevered from the

units

12, 13. The two

shaft sections

14, 15 are in each case driven independently of one another. To this end, in the illustrated example, each shaft section is assigned a

separate drive motor

16, 17 whose speed and/or direction of rotation can be changed. Output shaft of the

motors

16, 17

carry pulleys

18, 19 and

drive belts

20, 21 pass around these pulleys and

pulleys

22, 23 on the outermost ends of the

shaft sections

14, 15. Alternative drive transmissions could be provided instead of belts and pulleys, if preferred.

The bearing unit 12 is permanently fixed upon a common machine frame 24. Bearing unit 13, however, is supported thereon by a mounting which permits of limited axial displacement as well as transverse tilting of the unit 13. The mounting includes a table 25 carrying the bearing unit 13, and the table has a bearing bush 26 attached to its underside. The brush 26 can slide to and fro longitudinally on a bearing cylinder 27 in the direction of the arrow 28. The bush 26, and with it the table 25 is able to pivot about the axis 29 of the bearing cylinder 27. The bearing axis 29 is disposed parallel to but spaced from the central axis 4 of the mixer vessel and the

shaft sections

14, 15, but coincides with the shaft axis of the drive motor 17 and the axis of the pulley 19. This design makes it possible to pivot or tilt the table and bearing unit 13 without interrupting the drive connection between the motor 17 and the associated shaft section 15. Axial displacement can be produced by a pneumatic or hydraulic actuator, or by a spindle adjuster mechanism. A spindle drive for axial adjustment has been indicated in FIG, 4 simply by a handcrank 30. To swing the bearing unit 13 about the axis 29, a spindle drive mechanism 31 equipped with a handwheel 32 is shown. This mechanism, too, can be replaced by alternative drive arrangements, such as exemplified above in connection with the axial adjustment. To support the illustrated drive mechanism 31, which is articulated at 33 to the bearing unit 13, a mounting plate 34 on the machine frame 24 is used, as seen in FIG. 4.

Once the flange connection between the two central sections 6, 7 has been released, the parts of the machine section located (in FIG. 1) to the right of the central plane 9 can be displaced slightly to the right in the direction of the arrow 28 and then swung out of the way so that the vessel interior is quickly and easily ac cessible. In the illustrated example, axial displacement simply serves to clear mutual centring engagement between the vessel sections 6, 7 so that the ensuing pivoting motion can take place. It would be possible, however, simply to displace the entire machine section disposed to one side of the central plane 9 (in FIG. 1), axially along a suitably dimensioned slide way rather than to tilt, as described above, in order to move apart the adjacent ends of the vessel sections 6, 7, apart for access to the machine interior.

Furthermore, it is feasible for both bearing

units

12, 13 to be slidable and/or pivotable.

As the illustration of FIG. 5 shows in more detail, the innermost ends of the shaft sections l4, 15 are close to gether but are slightly spaced apart, terminating at either side of the main plane 9. A plurality of tool sets 35, 36, 37, 38 and 25, 36', 37', 38 and 39', which will be described in more detail hereinafter, are carried by the two shaft sections l4, 15 respectively.

The tool set 35 located closest to the outer end of the shaft section 14, has an annular hub 40 slipped over the shaft section 14 and is secured thereto in a rotational driving relationship by means of a spring ring element, details of which are omitted for clarity. Four tool blades or paddles 41 are fitted to the hub 40, the paddles being spaced apart at intervals around the hub periphery. The tool blades or paddles 41, as illustrated, are skewed, relative to a radial plane through the hub 40 and have symmetrical triangular prismatic crosssections, in the manner of a propeller. Accordingly the paddles impart to incoming material to be mixed a component of motion directed in the main transfer direction D when shaft section 14 is rotated. At or close to its left-hand end (in FIG. 5), the hub 40 has a set of four terminal tool blades 42 uniformly distributed about its periphery. The blades 42 have a symmetrical triangular prismatic cross-section and each has a flat side 43 disposed in a radial plane normal to the axis 4. As a result of their design, each of the tool blades 42, always exerts upon incoming material a driving force in the main transfer direction D, irrespective of the particular direction of rotation of the shaft section 14. In effect the blades 42 constitute clearing elements which keep the terminal plate 44 of the mixing chamber 45 free of material being mixed.

The tool set 36 also has an annular hub 46 which is simply slipped on to the shaft section 14 but is not in driving engagement therewith, however. Instead, the hub 46 is driven by the first hub 40. To this end, axial drive pins transmit drive from the neighbouring hub 40, to hub 46, the pins engaging in corresponding bores in the hub 40 and in the hub 46. To effect this drive or coupling between the hubs, there are at least two, but preferably three or more drive pins and corresponding pairs of bores, which are uniformly distributed circumferentially. Fundamentally, numerous drive pins and corresponding bores will be preferred because this makes it possible to stagger the hubs and their blades circumferentially in relation to one another. The larger the number of drive pins and bores, the finer is the incremental adjustment which is possible in this stagger. The hub 46 carries a group of blades or paddles 41 akin to the paddles on the first hub 40 and also skew-orien tated.

Proceeding inwardly of the tool set 36 is the adjoining tool set 37. This tool set comprises a hub 47 which once again carries four tool blades 48, the blades 48 being circumferentially staggered relative to the blades of tool set 36. Like all the tool blades, blades 48 extend almost to the internal wall of the vessel 1. The tool blades 48 here have a skew, or angle of incidence corresponding to that of the tool blades 41. The tool set 38 which then follows, likewise has an annular hub 49 identical to hub 47 but carrying at its circumference a set of tool blades 50 which are oppositely skewed relative to the blades 41. Express reference is made to the drawing for the angles of incidence of the blades of the different groups thereof. For the rest, the tool blades 50 are identical in configuration to those 48. Again, between the hubs 47, 49 and 47, 46, there is the drive pin connection of the form already described, this being shown in the cut-away illustration of FIG. 5. Here, the drive pins 51 can clearly be seen. As FIG. 5 clearly shows, the other tool sets on the shaft section 14 proceeding inwardly in the direction of the main plane 9, alternate in type between the designs of the tool sets 37 and 38. The innermost tool set 39 also possesses a hub 52 and, united therewith and embracing the innermost end of the shaft section 14, a cap or cover 53. By means of a set of axial screws (not shown) distributed around the shaft axis 4, the cap 53 is attached to the internal end of the shaft section so that the tool set 39, with its hub and cap portion, secures all the assembled row of tool sets on this shaft section. The circumference of the hub 52 carries blades 54 which correspond to those 50 of the tool set 38.

The design of the tool sets on the shaft section is similar to that employed in respect of the shaft section 14, so that as far as the illustration of the parts in the drawing is concerned, no .further explanation is required here. In principle, the tool sets on the shaft section 15 are disposed in a mirror symmetrical arrangement, about the main plane 9, in relation to those on the shaft section 14. One exception here, however, is the tool set 39' whose blades 55 have a skew or angle of incidence which is identical to that of the blades 54 of the tool set 39. In this fashion, straight forward transfer of material from the vessel section 6, to the left of the main plane to the vessel section 7 located at the right thereof, is ensured. As can be seen, the hubs of the tool sets arranged on the

shaft sections

14, 15 together form a casing surrounding the shaft sections. The shaft sections simply perform a supporting function and are not in rotary engagement with each of the tool sets. This design is not only particularly simple constructionally and cheap to manufacture, but also makes possible rapid assembling, and dismantling of the tool sets. Once the end tool sets 39, 39 have been released, the remaining sets can be drawn off axially and slipped back on again, without difficulty. With a similarly favourable facility for the straightforward balancing of the components which are involved in rotational motion, it is thus possible, using simple means, to vary the particular arrangement and relationship of tool sets on the shaft section in an arbitrary fashion and thus take account of conditions arising when mixing and preparing the most varied kinds of bulk materials. By employing blade arrangements which partially produce displacement in the transfer direction, other blade arrangements acting in opposition to the transfer direction or still further blade arrangements producing no net axial effect, and/or by changing the speed and/or direction of rotation of at least one shaft section, it is possible to effect a zonal variation in the eddying action and in the transfer speed or time of dwell of material being mixed in the machine, as may be required. Using spacers which simply constitute hub rings without blades and which are also coupled through axial drive pins, to neighbouring tool bearing hubs, the axial intervals between groups of tools can likewise be rapidly and simply adapted to meet the particular mixing requirements.

Although not illustrated in the drawings, the mixing vessel can be constructed from several part-cylindrical sections, in accordance with German Patent application No. 17821 15, which corresponds to US. Pat. No. 3,722,831, which defines communicating mixing chamber sections combined to form an overall mixing chamber through a mechanism of mutual material transfer, in which mixing chamber sections there is in each case a separate tool carrier shaft with tool sets. With this kind of design, the two mixing chamber sections will conveniently be disposed horizontally adjacent one another, the machine then not having one cylindrical mix ing vessel 1 but for example an overall vessel made up of two part-cylindrical vessels. Within each part vessel, the arrangement and embodiment of components described in FIG. 5, would then be retained.

Although the invention is illustrated and described with reference to a plurality of preferred embodiments thereof, it is to. be expressly understood that it is in no way limited to the disclosure of such a plurality of preferred embodiments, but is capable of numerous modifications within the scope of the appended claims.

We claim:

1. A machine for the continuous mixing of particulate materials, comprising:

a substantially horizontally-disposed cylindrical mixer vessel,

a material feed opening and a material discharge opening at opposite ends of said vessel,

a rotatable, horizontal tool carrier axially disposed within said vessel, and

a plurality of mixer paddle tools for rotation in said vessel mounted on said tool carrier, said paddle tools including paddles which extend radially towards and terminate adjacent an inner wall of said vessel,

said tools being detachably mounted on said tool carrier, and said tool carrier comprising two independent shafts disposed in line with one end of each shaft projecting outwardly from an associated end of said vessel,

two bearing units each rotatably receiving the outwardly-projecting ends of a different one of the tool carrier shafts,

separate rotary drive means coupled to said tool carrier shafts,

said mixer vessel comprises at least two vessel sections which meet at a radial joint plane, adjacent inner ends of said tool shafts being disposed on either side of said joint plane,

portion of said machine is located to one side of said joint plane, and means for supporting said portion for axial shifting movement relative to the remainder of said machine on the opposite side of said plane to allow access to the interior of sai'd'vessel and pivotal movement relative to the remainder of said machine on the opposite side of said plane to allow access to the interior of said vessel, the axis of movement of pivotal portion being disposed parallel to and spaced from the common axis of the aligned tool carrier shafts.

2. A machine according to claim 1, wherein said drive means are operable to control the rotation of their associated tool shafts independently of each other.

3. A machine according to claim 1, wherein said mixing vessel includes four vessel sections, two middle sections thereof adjoining one another at said joint plane, and the remaining two vessel sections respectively clefining feed and discharge zones at the opposite ends bf -5' said mixing vessel.

4. A machine according to claim 1, characterised in that at least some of said paddle tools have skewed pro- 8 peller-like paddle blades for imparting linear motion to material being mixed when said tool carrier is rotated.

5. A machine according to claim 1, wherein said paddle tools have paddle blades, said blades of the paddle tools mounted nearest to the outer end of each shaft each have a symmetrical triangular prismatic cross-section. one face thereof lying in a radial plane.

6. A machine according to claim 5, wherein at least a part of the paddle blades mounted on said shaft are oriented oppositely with respect to another part of said paddle blades mounted on said shaft.

7. A machine according to claim 1, wherein said mixing vessel comprises a plurality of part-cylindrical sections which define communicating mixing chamber sections and are combined into an overall mixing chamber to produce mutual material transfer.

8. A machine according to claim 1, wherein said paddle tools are mounted on a plurality of separate contiguous hubs, each hub serving as a detachable mounting for a plurality of paddle tools, each hub having pin-andhole drive coupling means confronting an adjacent hub to drivingly and detachably connect a pair of adjacent hubs, the hub mounted closest to the axial end of said vessel being drivingly connected to one of said carrier shafts, drive means and a cap mounted on the free end of each one of said shafts for retaining said plurality of hubs thereon.

Claims

1. A machine for the continuous mixing of particulate materials, comprising: a substantially horizontally-disposed cylindrical mixer vessel, a material feed opening and a material discharge opening at opposite ends of said vessel, a rotatable, horizontal tool carrier axially disposed within said vessel, and a plurality of mixer paddle tools for rotation in said vessel mounted on said tool carrier, said paddle tools including paddles which extend radially towards and terminate adjacent an inner wall of said vessel, said tools being detachably mounted on said tool carrier, and said tool carrier comprising two independent shafts disposed in line with one end of each shaft projecting outwardly from an associated end of said vessel, two bearing units each rotatably receiving the outwardlyprojecting ends of a different one of the tool carrier shafts, separate rotary drive means coupled to said tool carrier shafts, said mixer vessel comprises at least two vessel sections which meet at a radial joint plane, adjacent inner ends of said tool shafts being disposed on either side of said joint plane, a portion of said machine is located to one side of said joint plane, and means for supporting said portion for axial shifting movement relative to the remainder of said machine on the opposite side of said plane to allow access to the interior of said vessel and pivotal movement relative to the remainder of said machine on the opposite side of said plane to allow access to the interior of said vessel, the axis of movement of pivotal portion being disposed parallel to and spaced from the common axis of the aligned tool carrier shafts.

3. A machine according to claim 1, wherein said mixing vessel includes four vessel sections, two middle sections thereof adjoining one another at said joint plane, and the remaining two vessel sections respectively defining feed and discharge zones at the opposite ends of said mixing vessel.

4. A machine according to claim 1, characterised in that at least some of said paddle tools have skewed propeller-like paddle blades for imparting linear motion to material being mixed when said tool carrier is rotated.

5. A machine according to claim 1, wherein said paddle tools have paddle blades, said blades of the paddle tools mounted nearest to the outer end of each shaft each have a symmetrical triangular prismatic cross-section, one face thereof lying in a radial plane.

8. A machine according to claim 1, wherein said paddle tools are mounted on a plurality of separate contiguous hubs, each hub serving as a detachable mounting for a plurality of paddle tools, each hub having pin-and-hole drive coupling means confronting an adjacent hub to drivingly and detachably connect a pair of adjacent hubs, the hub mounted closest to the axial end of said vessel being drivingly connected to one of said carrier shafts, drive means and a cap mounted on the free end of each one of said shafts for retaining said plurality of hubs thereon.