EP3225300A1 - Mixing tool, mixing device and mixing tool manufacturing method - Google Patents

Abstract

The invention relates to a mixing tool, in particular a mixing blade, a mixing device with such a mixing tool and a method for producing such a mixing tool. The mixing tool is formed with a mounting portion (2) for attachment to a mixing arm of a mixing apparatus and a stripping portion (4) connected to the mounting portion (2) having a scraping edge (41) for scraping mix from a wall of a mixing tank of the mixing apparatus wherein the attachment portion (2) and the stripping portion (4) are formed of a metallic core (6) surrounded by a plastic shell (7) and wherein the scraping edge (41) is formed by at least one cemented carbide element (5).

Description

The invention relates to a mixing tool, in particular a mixing blade, a mixing device with such a mixing tool and a method for producing such a mixing tool.

Such mixing tools are used to mix building materials, in particular coarse-grained material, for example cement, mortar or concrete. For this purpose, the building material is filled in a mixing container in which the mixing tool, in particular designed as a mixing blade, is rotatably mounted on a mixing arm relative to the mixing container. In this case, either the mixing container can be fixed and the mixing arm can be rotatably mounted, or vice versa.

Due to the contact with the granular building material, it can quickly lead to wear on the mixing tool to minor or major damage to its surface. The mixing tool must then be repaired or even replaced. To increase the durability of the mixing tool, they are often partially or completely covered with a plastic, for example by means of polyurethane. When used in the mixing apparatus, the mixing tool serves not only to mix the building material in the mixing tank, but also to scrape or strip off building material fixed to tank walls of the mixing tank. In this case, in particular scraping along the container wall scraping edge of the mixing tool is extremely stressed. The plastic is slightly damaged and leads to a rapid wear of the mixing tool.

It is an object of the invention to provide a mixing tool with a longer shelf life.

The object is achieved according to the invention by a mixing tool having the features of claim 1, by a mixing device having the features of claim 9 and by a mixing tool manufacturing method having the features of claim 10. Advantageous developments of the invention are listed in the subclaims.

The invention is based on the idea to form the scraping edge made of hard metal in a plastic mixing tool. That is, one or more cemented carbide elements are attached to the mixing tool that provide or form the scraping edge. The hard metal element is preferably formed from sintered hard metal, in particular from sintered carbide hard metal. Preferably, it is made as a composite of tungsten carbide and the binder Cobald.

The scraping edge is arranged on a stripping section of the mixing tool and serves to strip mix from the wall of the mixing container. In order to fix the mixing tool on the mixing arm, it has a mounting portion which is rigidly or elastically connected to the stripping section. Fastening portion and stripping together have a metallic core, which is surrounded by a plastic sheath.

The mixing tool is made by first connecting the metallic core to the cemented carbide element. Subsequently, the entire arrangement of core and hard metal element is introduced into a mold, which is then filled with a Kunststoffgießmaterial. The plastic casting material is a precursor of the plastic from which the plastic jacket is formed. In particular, it may be a mixture of two or more components, which then solidify to the desired plastic. Only after curing of the Kunststoffgießmaterials so the finished plastic jacket with the desired hardness. The curing process can take a few minutes or more. Furthermore, the curing process may occur at ambient temperature or under heat.

Subsequently, the finished mixing tool is removed from the mold and optionally reworked. For example, it may be necessary to remove plastic covering the hard metal element (s). The arrangement of the core and the hard metal element is preferably arranged in the casting mold before filling with the plastic casting material such that when the casting mold is loaded with the plastic casting material, the hard metal element or at least the scraping edge is essentially not covered. This can be achieved, in particular, by the fact that the scraping edge bears against or touches a casting mold wall of the casting mold.

In a preferred embodiment, provision is made for a first core section assigned to the fastening section to be rigidly connected to a second core section assigned to the stripping section. The connection is preferably a welded connection between the two core sections. Alternatively, the first and second core portions may also be integrally formed, for example, manufactured as a single metal casting. Preferably, however, the core is composed of a plurality of metallic elements which are welded together. The metallic core can in particular be made of steel, for example of tool steel, or have metallic elements made of steel or tool steel.

In an advantageous development, it is provided that a first core section assigned to the fastening section is elastically and / or hingedly connected to a second core section assigned to the wiper section. That the first core portion is associated with the attachment portion means that the attachment portion is formed of the first core portion and the part of the plastic shell surrounding or covering the first core portion. The same applies to the stripping section and the second core section. An elastic and / or articulated connection between the two core sections has the consequence that, due to the plastic jacket surrounding both core sections, the connection between the fastening section and the wiper section is also deformable and preferably elastic. This means that the stripping section is movable relative to the fastening section, preferably elastically movable. Since the wiping edge is formed on the wiper portion, this has the consequence that the wiper can yield when in contact with obstacles, such as dents or smaller bumps in the wall of the mixing container, without risking damage to the mixing tool, for example due to splintering of the cemented carbide element.

In any event, the first core portion has one or more fasteners to secure the mixing tool to the mixing arm. The fastening element may for this purpose for example have an opening, a profile with a groove, for example a C-profile, and / or a threaded element. Furthermore, the plastic sheath is preferably formed in one case from a cast, so in particular has no seams.

The articulated or elastic connection between the two core sections can be formed exclusively by the plastic jacket. Preferably, however, a mechanical joint is additionally or alternatively formed between the two core sections, which also exists without the plastic jacket. In an expedient embodiment, it is provided that one of the two core sections has an extension, in particular a pin-shaped or tongue-shaped extension, which protrudes into a recess in the other core section. In particular, the extension may be formed on the first core portion. Preferably, two or more such extensions are formed on the one core section which are inserted into two or more openings of the other core section during manufacture of the mixing tool. Subsequently, a closing element at ends of Lugs soldered or welded to make the articulated connection between the core sections.

In the production of a mixing tool with an articulated or elastic connection between the two core sections, the two core sections are thus movable relative to one another, preferably pivotable relative to one another about an oscillating axis. In this case, it is advantageous to fix the two core sections against each other before or during the placing in the mold. This is preferably done by the mold is formed so that the two core sections can not move against each other therein.

According to a preferred embodiment, it is provided that the hard metal element is welded or soldered to the metallic core. This is preferably done by brazing. In any case, preferably a plurality of cemented carbide elements are strung together along the scraping edge. The hard metal elements are preferably sickle-shaped. At an end face or end edge of the mixing tool and other hard metal elements may be arranged to protect the mixing tool there from wear.

Preferably, it is provided that the metallic core is covered or surrounded by the plastic jacket and / or by the hard metal element to more than 70%, 80%, 85%, 90%, 95% or substantially completely. These percentages relate in particular to the surface of the metallic core. Preferably, the metallic core is substantially completely covered except for end faces and fastening elements, optionally having exposed end faces perpendicular to the wiping edge. This is about protecting the metallic core from wear by means of the plastic sheath or hard metal element.

In a preferred embodiment, it is provided that the metallic core is divided into a plurality of segments attached to one another. The metallic core is preferably segmented along the scraping edge. The Segments of the metallic core may in particular be formed substantially identical. These segments may also be secured to each other by means of joining elements, for example by means of welding, prior to the manufacture of the plastic sheath.

Preferably, the hard metal element or the hard metal elements is embedded in the plastic jacket. This means that one, two or more outer surfaces of the hard metal element is / are aligned with a mantle surface of the plastic jacket.

In an advantageous development, it is provided that the plastic sheath is formed from polyurethane. Preferably, the polyurethane has a Shore hardness in a range between 65 and 90 Shore A.

Fig. 1

ein Segment eines Mischwerkzeugs;

Fig. 2

ein weiteres Segment des aus der Fig. 2 Mischwerkzeugs;

Fig. 3

eine Querschnittsansicht der Segmentes aus der Fig. 2;

Fig. 4

eine Querschnittsansicht der Segmentes aus der Fig. 1;

Fig. 5

eine Seitenansicht des metallischen Kerns des Segmentes aus der Fig. 1, mit hieran befestigten Hartmetallelementen;

Fig. 6

ein nicht segmentiertes Mischwerkzeug;

Fig. 7

eine Seitenansicht eines gelenkig aufgebauten metallischen Kerns, mit hieran befestigten Hartmetallelementen;

Fig. 8

eine perspektivische Ansicht des Kerns aus der Fig. 7 mit Kunststoffmantel; und

Fig. 9

eine Explosionszeichnung der Anordnung aus der Fig. 7.

The invention will be explained below with reference to embodiments with reference to the figures. Hereby show:

Fig. 1

a segment of a mixing tool;

Fig. 2

another segment of the out of the Fig. 2 Mixing tool;

Fig. 3

a cross-sectional view of the segment of the Fig. 2 ;

Fig. 4

a cross-sectional view of the segment of the Fig. 1 ;

Fig. 5

a side view of the metallic core of the segment of the Fig. 1 with cemented carbide elements attached thereto;

Fig. 6

a non-segmented mixing tool;

Fig. 7

a side view of a hinged metallic core, with attached thereto cemented carbide elements;

Fig. 8

a perspective view of the core of the Fig. 7 with plastic sheath; and

Fig. 9

an exploded view of the arrangement of the Fig. 7 ,

In the Fig. 1 a segment of a mixing tool is shown schematically. It has a mounting portion 2 and a stripping portion 4, wherein the subdivision into mounting portion 2 and stripping portion 4 is not strict takes place along a dividing line. The attachment section 2 serves to fasten the mixing tool to a mixing arm, while the stripping section 4 has a scraping edge 41, by means of which mix can be scraped off or scraped off from a wall of a mixing container (not shown in the figures). The wiping edge 41 is formed by means of hard metal elements 5, which are lined up along the mixing tool in the direction of the wiping edge 41 to each other.

It can be seen on an end face 11 of the mixing tool segment that the segment is formed from a metallic core 6 and a plastic sheath 7 of polyurethane surrounding this core 6. The metallic core 6 of tool metal is composed of several parts which are welded together. These include a first core portion 62, which is formed as a C-profile and thus has a groove. This groove forms a fastening element with which the attachment of the mixing tool takes place on the mixing arm. Furthermore, the core 6 has a two core portion 64, to which the hard metal elements 5 are fixed by means of brazing. Further parts of the metallic core 6 further form a connecting piece 63, which rigidly connects the first core portion 62 to the second core portion 64, and a stiffening piece 65, which is fastened to the first core portion 62 and serves to ensure that the plastic jacket 7 is stable in its shape shown here reserves.

At the in Fig. 1 The segment shown may be an end segment or a middle segment of the mixing tool. In certain embodiments, the entire mixing tool can also only one segment as in Fig. 1 represented exist. Preferably, the mixing tool in addition to the in Fig. 1 still shown in the segment Fig. 2 represented segment on which, however, can also serve as an independent mixing tool. In addition to the carbide elements 5 arranged along the scraping edge 41, it has two further hard metal elements 51, which are arranged on the end face 11, and there protect a front edge of the mixing tool against wear.

In the Fig. 3 is a cross-sectional view of the segment from the Fig. 2 shown parallel to the end face 11. Here it can be seen that the further hard metal elements 51 are soldered onto carrier elements 66, which as part of the metallic core 6 are likewise fastened to the first core section 62 and the second core section 64 by means of welding.

The Fig. 4 shows a cross section of the segment of the Fig. 1 and / or also of the segment from the Fig. 2 but further away from the end face 11 to which the further hard metal elements 51 are attached. Therefore, the other hard metal elements 51 are not visible here. Instead, joining elements 8 are shown, which serve to assemble several such segments into a mixing tool. The joining elements 8 are welded to the metallic cores 6 of two or more mixing tool segments before the plastic shell 7 is formed around it.

In the Fig. 4 It is clearly visible that on the hard metal element 5 both a front surface 12 and a bottom surface 13 are flush with associated surfaces of the plastic jacket 7 or merge into them. This ensures that the mixing tool has a flat front surface 12 and a flat lower surface 13 without recesses or elevations, which could be attack surfaces for wear.

In the Fig. 5 is the metallic core 6 of the segment of the Fig. 1 represented with the brazed carbide element 5. For the subsequent production of the plastic sheath 7, the arrangement of the Fig. 5 preferably introduced in a direction perpendicular to the image plane in a mold, which in cross-section the shape of the plastic sheath of the Fig. 4 having. Subsequently, the mold is charged or filled with a Kunststoffgießmaterial. When the plastic casting material is cured, the plastic shell 7 is then formed.

The Fig. 6 shows a mixing tool, which is not made in segmental construction. Here, only the plastic sheath 7 and the hard metal elements 5 are visible, which form the scraping edge 41. The metallic core 6, which is also present in this embodiment and to which the hard metal elements 5 are soldered, is not visible since it is completely covered by the plastic jacket 7 and the hard metal elements 5. In addition one sees in the Fig. 6 Fasteners 621 in the form of holes, which serve to attach the mixing tool to a mixing arm.

Another embodiment for a mixing tool will now be described with reference to FIG Fig. 7, 8 and 9 explained. This is a mixing tool, which is also developed in the form of a segment that can be joined together with one or more other similar segments to a mixing tool with a larger wiper edge 41. Unlike in the Fig. 1 to 5 shown mixing tool segments, the mixing tool from the Fig. 7 to 9 an elastic connection between the attachment portion 2 and the stripping portion 4. This is achieved in that the metallic core 6 forms a joint between the first core section 62 and the second core section 64. If the metallic core 6 is then provided with a plastic jacket 7, then the elastic connection is formed.

In the Fig. 7 alone, the metallic core 6 is shown with a soldered to the second core portion 64 carbide element 5 in a side view. The Fig. 8 shows the surrounded with the plastic core 7 made of polyurethane metallic core 6 of the Fig. 7 , And the Fig. 9 shows an exploded view of each in the Fig. 7 represented parts.

Unlike the blending tool with rigid connection between the first core portion 62 and the second core portion 64, in the present embodiment, the connecting member 63 is replaced by a first hinge member 631 and a second hinge member 632 which engage with each other. For this On the first joint element 631 tongue-shaped joint element extensions 634 are formed, which engage in the joint element recess 635 of the second joint element 632. After inserting the hinge element extensions 634 into the hinge element recess 635, a pin-shaped end member 633 is welded to the ends of the hinge element extensions 634 to hold the second hinge element 632. As a result, the two hinge elements 631, 632 are mutually movable to a certain degree. Depending on the strength and elasticity of the plastic jacket 7, this results in the finished mixing tool to a more or less elastic mobility between the trained as a fastener first core portion 62 and the hard metal elements 5, so that the mixing tool when touching a survey on the mixing vessel wall at the wiping edge is formed more or less compliant.

In a modified embodiment, the pin-shaped end element 633 and / or the first joint element 631 is missing. At least in this embodiment, the second joint element 632 without the plastic shell 7 is not coupled to the first core section 62. In this case, the second joint element 632 is therefore connected exclusively to the first core section 62 by means of the plastic jacket 7.

The other elements of the mixing tool according to the Fig. 7 to 9 correspond to the elements of the mixing tool according to the Fig. 7 to 91 to 5, if they bear the same reference numerals. In addition, also in the mixing tool according to the Fig. 7 to 9 further carbide elements 51 may be provided on the end face 11 of a segment.

LIST OF REFERENCE NUMBERS

11

face

12

front surface

13

undersurface

2

attachment section

4

stripping
41 wiper edge

5

Carbide element
51 additional carbide element

6

metallic core
62 first core section
621 fastener
63 connector
631 first joint element
632 second joint element
633 end element
634 joint element extension
635 joint element recess
64 two core section
65 stiffener
66 carrier element

7

Plastic sheath

8th

joining element

Claims (10)

Mixing tool, in particular mixing blade, with a fastening section (2) for attachment to a mixing arm of a mixing device and a stripping section (4) connected to the fastening section (2), which has a scraping edge (41) for stripping mixed material from a wall of a mixing vessel of the mixing device wherein the attachment portion (2) and the stripping portion (4) are formed of a metallic core (6) surrounded by a plastic shell (7) and wherein the scraping edge (41) is formed by at least one cemented carbide element (5). Blending tool according to Claim 1, characterized in that a first core section (62) assigned to the fastening section (2) is rigidly connected to a second core section (64) assigned to the stripping section (4). Mixing tool according to Claim 1, characterized in that a first core section (62) assigned to the fastening section (2) is connected elastically and / or hingedly to a second core section (64) assigned to the wiper section (4). Mixing tool according to claim 1, characterized in that one of the two core sections (62; 64) has a pin-shaped or tongue-shaped extension (634) which projects into a recess (635) in the other core section (64; 62). Mixing tool according to one of the preceding claims, characterized in that the hard metal element (5) is welded or soldered to the metallic core (6). Mixing tool according to one of the preceding claims, characterized in that the metallic core (6) through the Plastic shell (7) and / or by the hard metal element (5) to more than 70%, 80%, 85%, 90%, 95% or substantially completely covered. Mixing tool according to one of the preceding claims, characterized in that the metallic core (6) is subdivided into several segments fastened to one another. Mixing tool according to one of the preceding claims, characterized in that the plastic jacket (7) is formed from polyurethane. Mixing device with a mixing container, a mixing arm, wherein the mixing container and the mixing arm are rotatably mounted against each other, and a mounted on the mixing arm Molding tool according to one of the preceding claims. Blending tool manufacturing method comprising the following steps: - Providing a metallic core (6); - Attaching at least one hard metal element (5) to the metallic core (6); - placing the metallic core (6) with the hard metal element (5) in a mold; - filling the mold with a Kunststoffgießmaterial; and - Curing the Kunststoffgießmaterials to a metallic core (6) surrounding the plastic sheath (7).

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