WO2007085436A1

WO2007085436A1 - Device for mixing or conveying an abrasive material

Info

Publication number: WO2007085436A1
Application number: PCT/EP2007/000601
Authority: WO
Inventors: Reinold Erner
Original assignee: Schwing Gmbh
Priority date: 2006-01-24
Filing date: 2007-01-24
Publication date: 2007-08-02
Also published as: DE102006003417A1

Abstract

The invention relates to a device for mixing or conveying an abrasive material with a driven spiral, which comprises at least two two-dimensional spiral segments adjoining each other in the course of the spiral and has a means for connecting the spiral segments, the spiral segments forming a lap joint, which extends over the region of the adjoining faces of the spiral segments that cover each other. The invention is based on the object of further developing the generic device in such a way that the service life of the spiral is prolonged by efficient means. The object is achieved by means for connecting the spiral segments (13, 14) being arranged in an integrated manner in the lap joint (16).

Description

Device for mixing or conveying an abrasive mass

The invention relates to a device for mixing or conveying an abrasive mass with a driven coil, which comprises at least two flat, helical segments adjoining each other in the helical course and has a means for connecting the helical segments, wherein the helical segments form a lap joint, which extends over the Area of the overlapping pads of the helical segments extends.

A device of the generic type can be found for example in stationary or mobile mixing drums for mixing mortar or concrete. It is well known that concrete is prefabricated by the manufacturer and transported in special truck mixers, on the frame of a rotatably mounted mixing drum rests to the destination, while the concrete in the mixing drum by means of one or more contained coils is constantly mixed to maintain its weiterverarbeitbare consistency to keep. The mixing drum is composed of several conical and cylindrical shell rings. The coil made of strip-shaped steel sheet is usually first manually fastened and completed in the composite mixing drum, by sections being formed with its radial outer contour on the inside wall of the mixing drum. is welded. For this purpose, the production staff with the helical material and its tools on the single opening, namely on the loading or unloading, get into the mixing drum and make the assembly work in its interior. The finished coil then passes in a spiral shape with variable radii along the inner wall of the various shell rings of the mixing drum.

A generic device is also found in larger agitators for mix or long augers for bulk material. All devices is common that the coil for manufacturing reasons, such as because of their overall length, due to variable radii of curvature or lack of accessibility during assembly, can not be made in one piece, but is composed of individual helix segments. These spiral segments of sheet steel sections are welded together to form the coil. In this case, a butt joint welding in which the helical segments butt against each other, usually not possible because the required for this tight tolerances in the position of the abutting edges of the helical segments to each other at the weld can not be guaranteed. The helical segments themselves are slightly curved, which may already result in deviations in the connection contour. Significant tolerances result particularly in that the helical segments are also to be fastened with the inner or outer contour on curved surfaces, such as cylinder or hollow cylinder jacket surfaces, such as during assembly of the helix on the inner wall of a mixing drum. Therefore, in such applications, the helix is mainly made a so-called lap joint welding of the helical segments, in which the steel plate bands are arranged overlapping and thus no great accuracy of the helical segments connection accuracy is required. The two-sided abutting edges of the helical segments, which rest on the surface of the other helical segment during the lap joint welding, are welded to the other helical segment by means of a standard fillet weld. This is also because, because of their size, welders for fillet welding can easily be incorporated into the size-limited, ie small, openings of the containers. A disadvantage of this construction of the helix is that the fillet welds are considerably exposed to wear. During operation of the rotating coil in a coarse-grained mix, such as concrete or mortar, the helical segments are mechanically stressed and worn down very much by abrasion. The coil raises, for example, in a substantially horizontally mounted and rotating mixing drum of a truck mixer the concrete to a certain height, where it rolls along the surfaces of the helical segments and then falls off the helix. In order to counteract the wear and to extend the service life of the helix, mainly wear-resistant mild steel sheets are used for the helical segments. However, the fillet welds of the helical segments constitute a weak point. They form, over the entire length of the abutting edge of the helix segments, an immediate direct contact surface for the moving mixture, which impinges against the direction of rotation of the helix on the abutment edge or fillet weld surface. This can weaken the cross section of the weld and prematurely release the weld joint of the abutting edge with the surface of the other helical segment, so that finally the connection of the helical segments can completely fail. In this case, it is already sufficient if the weld is only partially worn, because then mix can be pressed between the abutting edge and the surface of the other spiral segment and a region of the overlap can be widened. The weld is additionally subjected to tensile stress, which causes further damage.

From DE 3303971 Al a device and for mixing or conveying concrete mortar, as well as a method for reducing the wear of a working edge or working surface of a mortar mixer or conveyor is known. To reduce the wear of the working edge or the work surface, such as the mortar mixer helix, a device for holding mortar is provided on the working edge or a working surface to build up by the hardened mortar on the working edge or the working surface a protective mortar layer. In a helix fastened in the mixing drum on the inside wall side, the working edge or working surface refers to the radially inner edge - A -

the helix or on the surfaces of the spiral sheet. For this purpose, a gauzy reinforcement made of flexible expanded metal strips is placed on the area to be protected and held by spot welding. In operation, the mortar fills the openings of the sieve-like expanded metal construction, at the same time the mortar is held during a drum wash in the openings. Once the retained mortar has set, it forms a thin layer of reinforced concrete with the expanded metal screen which protects the helix and helix edge from wear.

The document also discloses an application of the solution for other wear-prone inner working surfaces of a mortar mixer, for example, areas of the drum wall. Obviously also conceivable would be a cover of the abutting edges or the fillet welds of the lap joint welding of the helical segments according to this known solution in order to protect them from wear. The disadvantage, however, is that on the one hand, the solution is limited only to a setting mix, such as concrete and mortar. On the other hand, the procedure would be very expensive to perform by each of the fillets over their entire length additionally covered manually with an expanded metal strip and attached by spot welding. This requires a lot of production time and thus causes high costs, which calls into question the economy of this design.

The invention therefore aims to develop the generic device for mixing or conveying an abrasive mass, such that the service life of the coil is increased by efficient means.

According to the invention this object is achieved by a device having the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, the means for connecting the helical segments is arranged integrated in the lap joint. This advantageous arrangement of the connection The helical segments provide a simple, effective and durable bond between the overlapping surfaces of the helical segments without exposing the components of the compound to excessive wear from the abrasive mass. The connection is protected in the lap joint integrated, so that specially takes the material of the helical segments the function of protecting the connection. In this way, only the abutting edges of the lap joint, which are directly exposed to the abrasive mass during rotation of the coil, are subject to wear rather than the concealed connection. The abrasion of the abutting edges is largely irrelevant to the durability of the compound. Over time, the abutting edges are ground so that an oblique face is created, which then dissipates the abrasive mass well and reduces the further wear of the abutting edges.

In this context, it is expedient that the pointing in the direction of rotation of the helix abutting edge of the lap joint is already chamfered with a corresponding phase, so that the abrasive mass can slide well on the lap joint and the wear of the abutting edge, is kept low from the outset. Are also opposite directions of rotation of the helix provided meaningful way, both abutting edges of the lap joint designed in such a way.

With the features of claim 2, a device can be realized with an even more durable and secure connection of the helical segments. A material connection of the spiral segments provides an insoluble, very strong connection of the materials to be joined together, for example sheet steel, in which the joining surfaces of the materials, mainly by the action of heat and / or pressure, materially unite. These cohesive connections withstand especially the effect of dynamic loads, as they occur at the helix stood.

It is particularly favorable if the material connection between the overlapping connecting surfaces of the helical segments can be generated, because in this case, according to the expected load, particularly large joining surfaces are made available can be. In addition, the position of the joining surfaces in relation to the expected Abriebrichtung allows only a maximum acting on the edge regions of the compound wear, which is irrelevant with a sufficiently large extent of the joining surfaces.

Preferably, the means for connecting the helical segments of a welded joint, a solder joint or an adhesive bond. These types of connections are inexpensive to produce with little effort and therefore especially for small series assembly by hand, such as in the assembly of the coil in a mixing drum, suitable. These types of connections also offer good repair or repair options.

With regard to the welded connection, the resistance spot welding has proven to be particularly advantageous. This type of welded joint is limited to the selective welding of the overlapping connecting surfaces, which can be produced by means of a handy spot welding device. Through the electrodes of the electrode welding gun, which press from both sides against the overlapping filament segments, flows a current that causes the material locally to melt due to the large contact resistance and point-shaped joints. This compound requires no welding additives, requires no special preparation of the welds and is done in extremely short welding time. These benefits are particularly evident during assembly work in a container, such as a mixing drum. With a few, distributed over the overlap of the helical segments welds the required connection forces are easily guaranteed, the handling of the spot welder also allows the realization of the compounds in quite inaccessible places of the helix, which can arise during assembly of the helix in the mixing drum. In addition, spot welding saves a considerable amount of time compared to other welded joints, which reduces production costs and, not least, the duration of the relatively uncomfortable and unhealthy working hours. situation of the manufacturing personnel during the welding work in the mixing drum.

According to an alternative embodiment, the helical segments in the lap joint corresponding recesses, wherein in the recesses a welded joint can be realized by a Füllnahtschweißung.

Here, in the overlapping overlapping recesses of the helical segments, a molten metallic filler material (solder) is usually introduced with the aid of a flux which not only selectively connects the helix segments after hardening. The solder fills in the liquid state, both the cavities of the recesses and creeps, due to the capillary action, also in the not directly accessible joints between the pads of the helical segments. In this case, with a few, distributed over the lap joint of the helical segments recesses a particularly dense connection of the helical segments achieved with good strength values. The melting temperature of the solder is below the melting temperature of the filament segments to be joined, so that this compound allows low operating temperatures and short production times during connection work.

Further, in a specific embodiment, the coil is connected to a mixing drum of a truck mixer or a stationary mixer or to a shaft of a stirrer or a screw conveyor. In these exemplary applications, the aforementioned advantages of the invention are particularly significant.

The device according to the invention will be explained in more detail below with reference to an embodiment with reference to the accompanying drawings. The accompanying drawings show in a schematic representation in FIG Fig. 1 is a perspective view of a truck mixer with a

Mixing drum

2 is a partial view of the mixing drum of the truck mixer with transparent view of two included coils according to the invention,

3 is a sectional view of a lap joint of the helical segments with a welded joint according to the prior art,

Fig. 4 is a sectional view of a lap joint of the helical segments with a compound according to the invention.

From Fig. 1, a truck mixer 1 with a mixing drum 2 can be seen. Such a truck mixer 1 is a commercial vehicle on the frame 3, a mixing drum 2 is rotatably mounted for the transport of mortar, concrete or the like. The factory finished concrete is filled by means of a funnel 4 at the loading opening 5 of the mixing drum 2 in this and mixed during transport to the construction site consistency preserving in the rotating mixing drum 2. The discharge of the concrete at the destination can according to the local requirements, for example by means of a conveyor system with swiveling concrete distributor masts 6, as shown in Fig. 1, take place, with which the concrete is pumped from the mixing drum 2 and conveyed via a entrained at the concrete distributor masts on site. Alternatively, the discharge of the concrete by means of a bulk material ramp 7, as shown in Fig. 2, take place. In this case, the mixing drum 2 is tilted, so that the concrete on the discharge opening 8 of the mixing drum meets the bulk material ramp 7 and can be unloaded on site. The mixing drum 2 itself consists of several abutting conical and cylindrical shell rings 9 and has one end over a closed bottom 10, which faces the loading or unloading 5.8.

Fig. 2 provides a transparent view into the interior of the mixing drum 2 of the truck mixer 1 on two included coils 1 according to the invention. Both coils 11 begin offset position on the bottom 10 of the mixing drum 2 and extend spirally along the inner wall 12 of the mixing drum 2 to the loading or unloading 5.8. The coils 1 1 are driven by the rotatable mixing drum 2, with which they are connected. Each of the helices 1 1 is composed of a plurality of mutually joined helical segments 13, 14, which are made of strip-shaped steel sheet. Width, length and thickness of the structural steel sheet can be approximately 250 mm x 1500 mm x 10 mm by way of example. For manual, stepwise attachment of the helices 11 in the mixing drum 2 is an elongated curved edge 15 of the respective helical segment 13,14, which results in the radially outer contour of the helix 11, welded to the inner wall 12 of the mixing drum 2, wherein the adjoining helix segments 13,14 ü overlap over their entire width and form a lap joint 16.

In each of FIGS. 3 and 4, such a lap joint 16 of the spiral segments 13, 14 can be seen in detail. 3 shows a sectional view of a welded connection of the spiral segments 13, 14 according to the prior art, namely by means of fillet weld welding. In this case, a first fillet weld 17 welds a butt edge 18 of the first filament segment 13 to the surface 19 of the adjoining second filament segment 14 and further a second fillet weld 20 forms a collision edge 21 of the second filament segment 14 with the surface 22 of the first filament segment 13. The fillet welds 17, 20 run along the abutting edges 18,21 over the entire width of the helical segments 13,14. In the region of a connection surface 23 of the first coil segment 13 and a connection surface 24 of the second coil segment 14, both coil segments 13, 14 overlap.

FIG. 4 illustrates in cross-section a connection according to the invention of the helical segments 13, 14 in the lap joint 16. All components of the compound are arranged integrated in the lap joint 16. In this particular embodiment, a welded connection 25 connects by resistance spot welding at a plurality of welding points 26, the connection surfaces 23,24 of the first and second coil segment 13,14 directly to each other. In the sectional For example, only one welding point 26 of the welding points 26 distributed over the connecting surfaces 23, 24 is visible.

The arrows shown in Fig. 3 and 4 illustrate according to the two possible directions of rotation 27 of the helix 1 1, the corresponding relative directions of movement 27 of the helical segments 13, 14 by the mixing or conveying concrete mass.

It can be seen in the fillet weld according to the prior art in Fig. 3 that the respective fillet 17,20 directly provides an attack surface for the mortar or concrete, which counter to the direction of rotation of the coil 27 to the abutting edge 18,21 and the fillet weld 17.20 impinges, so that the respective fillet 17,20 is considerably exposed to wear.

The resistance spot welding according to FIG. 4, on the other hand, produces a very effective material connection of the connection surfaces 23, 24 in a simple and efficient manner, without components of the welded connection 25 projecting beyond the lap joint 16. With a few, over the lap 16 of the helical segments 13,14 distributed welds 26, which can be easily and quickly set with the help of a suitable spot welder at all points of the helix 1 1 in the mixing drum 2, the necessary connection forces are realized without problems. The welding points 26 are fully integrated in the lap joint 16 and are thus protected from abrasion by the mortar or concrete. This eliminates the need for more elaborate and wear-prone fillet welds 17,20 at the abutting edges 18,21 of the helical segments 13,14 and ensures, on the other hand, that now only in the direction of rotation 27 of the helix 11 freely accessible, but in terms of wear harmless abutting edges 18,21 the spiral segments 13, 14 are exposed to abrasion by the mortar or concrete.

The invention is not limited to use in a mixing drum 2 of a truck mixer 1. Rather, it can also be used in other devices for mixing or conveying abrasive materials, such as, for example, for stationary concrete silos, for agitators in concrete works or for overburden conveyors.

Device for mixing or conveying an abrasive mass

LIST OF REFERENCE NUMBERS

Mixing drum Mixing drum Frame Hopper Loading opening Conveying system with swiveling concrete distributor mast Bulk material ramp Bottom of mixing drum Coil Inner wall First helix segment Second helix segment Long edge of helix segment Lap lap First fillet Butt of first helix segment Surface of second helix segment Second fillet Butt of second helix segment Surface of first helix segment Contact surface of first helix segment first helical segment Connecting surface of the second helical segment Weld connection Welding point Direction of rotation of the helix; Direction of movement of the spiral segments

Claims

Apparatus for mixing or conveying abrasive material claims

1. A device for mixing or conveying an abrasive mass with a driven coil, which comprises at least two flat, helically adjoining helical segments and has a means for connecting the helical segments, wherein the helical segments form a lap joint, which extends over the region of the overlapping Connecting surfaces of the helical segments extends, characterized in that the means for connecting the helical segments (13,14) in the lap joint (16) is arranged integrated.

2. Device according to claim 1, characterized in that with the means for connecting the helical segments (13,14) a material connection of the helical segments (13,14) can be generated.

3. A device according to claim 2, characterized in that the material connection between the overlapping connecting surfaces (23,24) of the helical segments (13,14) can be generated.

4. Apparatus according to claim 2 or 3, characterized in that the means for connecting the helical segments (13,14) consists of a welded joint (25), a solder joint or an adhesive bond.

5. Apparatus according to claim 4, characterized in that the welded connection (25) can be realized by a resistance spot welding.

6. The device according to claim 4, characterized in that the helical segments (13,14) in the lap joint (16) have corresponding recesses, wherein in the recesses a welded connection (25) can be realized by a Füllnahtschweißung.

7. Device according to one of the preceding claims, characterized in that in the direction of rotation of the helix (27) facing abutting edge (18,21) of the lap joint (16) is provided with a phase.

8. Device according to one of the preceding claims, characterized in that the helix (11) is connected to a mixing drum (2) of a driving mixer (1) or a stationary mixer.

9. Device according to one of the preceding claims, characterized in that the helix (11) is connected to a shaft of a stirrer or a screw conveyor.